1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Shared application/kernel submission and completion ring pairs, for
4 * supporting fast/efficient IO.
5 *
6 * A note on the read/write ordering memory barriers that are matched between
7 * the application and kernel side.
8 *
9 * After the application reads the CQ ring tail, it must use an
10 * appropriate smp_rmb() to pair with the smp_wmb() the kernel uses
11 * before writing the tail (using smp_load_acquire to read the tail will
12 * do). It also needs a smp_mb() before updating CQ head (ordering the
13 * entry load(s) with the head store), pairing with an implicit barrier
14 * through a control-dependency in io_get_cqe (smp_store_release to
15 * store head will do). Failure to do so could lead to reading invalid
16 * CQ entries.
17 *
18 * Likewise, the application must use an appropriate smp_wmb() before
19 * writing the SQ tail (ordering SQ entry stores with the tail store),
20 * which pairs with smp_load_acquire in io_get_sqring (smp_store_release
21 * to store the tail will do). And it needs a barrier ordering the SQ
22 * head load before writing new SQ entries (smp_load_acquire to read
23 * head will do).
24 *
25 * When using the SQ poll thread (IORING_SETUP_SQPOLL), the application
26 * needs to check the SQ flags for IORING_SQ_NEED_WAKEUP *after*
27 * updating the SQ tail; a full memory barrier smp_mb() is needed
28 * between.
29 *
30 * Also see the examples in the liburing library:
31 *
32 * git://git.kernel.dk/liburing
33 *
34 * io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
35 * from data shared between the kernel and application. This is done both
36 * for ordering purposes, but also to ensure that once a value is loaded from
37 * data that the application could potentially modify, it remains stable.
38 *
39 * Copyright (C) 2018-2019 Jens Axboe
40 * Copyright (c) 2018-2019 Christoph Hellwig
41 */
42 #include <linux/kernel.h>
43 #include <linux/init.h>
44 #include <linux/errno.h>
45 #include <linux/syscalls.h>
46 #include <net/compat.h>
47 #include <linux/refcount.h>
48 #include <linux/uio.h>
49 #include <linux/bits.h>
50
51 #include <linux/sched/signal.h>
52 #include <linux/fs.h>
53 #include <linux/file.h>
54 #include <linux/fdtable.h>
55 #include <linux/mm.h>
56 #include <linux/mman.h>
57 #include <linux/percpu.h>
58 #include <linux/slab.h>
59 #include <linux/bvec.h>
60 #include <linux/net.h>
61 #include <net/sock.h>
62 #include <net/af_unix.h>
63 #include <linux/anon_inodes.h>
64 #include <linux/sched/mm.h>
65 #include <linux/uaccess.h>
66 #include <linux/nospec.h>
67 #include <linux/highmem.h>
68 #include <linux/fsnotify.h>
69 #include <linux/fadvise.h>
70 #include <linux/task_work.h>
71 #include <linux/io_uring.h>
72 #include <linux/audit.h>
73 #include <linux/security.h>
74 #include <asm/shmparam.h>
75
76 #define CREATE_TRACE_POINTS
77 #include <trace/events/io_uring.h>
78
79 #include <uapi/linux/io_uring.h>
80
81 #include "io-wq.h"
82
83 #include "io_uring.h"
84 #include "opdef.h"
85 #include "refs.h"
86 #include "tctx.h"
87 #include "sqpoll.h"
88 #include "fdinfo.h"
89 #include "kbuf.h"
90 #include "rsrc.h"
91 #include "cancel.h"
92 #include "net.h"
93 #include "notif.h"
94
95 #include "timeout.h"
96 #include "poll.h"
97 #include "rw.h"
98 #include "alloc_cache.h"
99
100 #define IORING_MAX_ENTRIES 32768
101 #define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES)
102
103 #define IORING_MAX_RESTRICTIONS (IORING_RESTRICTION_LAST + \
104 IORING_REGISTER_LAST + IORING_OP_LAST)
105
106 #define SQE_COMMON_FLAGS (IOSQE_FIXED_FILE | IOSQE_IO_LINK | \
107 IOSQE_IO_HARDLINK | IOSQE_ASYNC)
108
109 #define SQE_VALID_FLAGS (SQE_COMMON_FLAGS | IOSQE_BUFFER_SELECT | \
110 IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
111
112 #define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
113 REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \
114 REQ_F_ASYNC_DATA)
115
116 #define IO_REQ_CLEAN_SLOW_FLAGS (REQ_F_REFCOUNT | REQ_F_LINK | REQ_F_HARDLINK |\
117 IO_REQ_CLEAN_FLAGS)
118
119 #define IO_TCTX_REFS_CACHE_NR (1U << 10)
120
121 #define IO_COMPL_BATCH 32
122 #define IO_REQ_ALLOC_BATCH 8
123
124 enum {
125 IO_CHECK_CQ_OVERFLOW_BIT,
126 IO_CHECK_CQ_DROPPED_BIT,
127 };
128
129 enum {
130 IO_EVENTFD_OP_SIGNAL_BIT,
131 IO_EVENTFD_OP_FREE_BIT,
132 };
133
134 struct io_defer_entry {
135 struct list_head list;
136 struct io_kiocb *req;
137 u32 seq;
138 };
139
140 /* requests with any of those set should undergo io_disarm_next() */
141 #define IO_DISARM_MASK (REQ_F_ARM_LTIMEOUT | REQ_F_LINK_TIMEOUT | REQ_F_FAIL)
142 #define IO_REQ_LINK_FLAGS (REQ_F_LINK | REQ_F_HARDLINK)
143
144 static bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
145 struct task_struct *task,
146 bool cancel_all);
147
148 static void io_queue_sqe(struct io_kiocb *req);
149
150 struct kmem_cache *req_cachep;
151 static struct workqueue_struct *iou_wq __ro_after_init;
152
153 static int __read_mostly sysctl_io_uring_disabled;
154 static int __read_mostly sysctl_io_uring_group = -1;
155
156 #ifdef CONFIG_SYSCTL
157 static struct ctl_table kernel_io_uring_disabled_table[] = {
158 {
159 .procname = "io_uring_disabled",
160 .data = &sysctl_io_uring_disabled,
161 .maxlen = sizeof(sysctl_io_uring_disabled),
162 .mode = 0644,
163 .proc_handler = proc_dointvec_minmax,
164 .extra1 = SYSCTL_ZERO,
165 .extra2 = SYSCTL_TWO,
166 },
167 {
168 .procname = "io_uring_group",
169 .data = &sysctl_io_uring_group,
170 .maxlen = sizeof(gid_t),
171 .mode = 0644,
172 .proc_handler = proc_dointvec,
173 },
174 {},
175 };
176 #endif
177
io_submit_flush_completions(struct io_ring_ctx * ctx)178 static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
179 {
180 if (!wq_list_empty(&ctx->submit_state.compl_reqs) ||
181 ctx->submit_state.cqes_count)
182 __io_submit_flush_completions(ctx);
183 }
184
__io_cqring_events(struct io_ring_ctx * ctx)185 static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
186 {
187 return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
188 }
189
__io_cqring_events_user(struct io_ring_ctx * ctx)190 static inline unsigned int __io_cqring_events_user(struct io_ring_ctx *ctx)
191 {
192 return READ_ONCE(ctx->rings->cq.tail) - READ_ONCE(ctx->rings->cq.head);
193 }
194
io_match_linked(struct io_kiocb * head)195 static bool io_match_linked(struct io_kiocb *head)
196 {
197 struct io_kiocb *req;
198
199 io_for_each_link(req, head) {
200 if (req->flags & REQ_F_INFLIGHT)
201 return true;
202 }
203 return false;
204 }
205
206 /*
207 * As io_match_task() but protected against racing with linked timeouts.
208 * User must not hold timeout_lock.
209 */
io_match_task_safe(struct io_kiocb * head,struct task_struct * task,bool cancel_all)210 bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
211 bool cancel_all)
212 {
213 bool matched;
214
215 if (task && head->task != task)
216 return false;
217 if (cancel_all)
218 return true;
219
220 if (head->flags & REQ_F_LINK_TIMEOUT) {
221 struct io_ring_ctx *ctx = head->ctx;
222
223 /* protect against races with linked timeouts */
224 spin_lock_irq(&ctx->timeout_lock);
225 matched = io_match_linked(head);
226 spin_unlock_irq(&ctx->timeout_lock);
227 } else {
228 matched = io_match_linked(head);
229 }
230 return matched;
231 }
232
req_fail_link_node(struct io_kiocb * req,int res)233 static inline void req_fail_link_node(struct io_kiocb *req, int res)
234 {
235 req_set_fail(req);
236 io_req_set_res(req, res, 0);
237 }
238
io_req_add_to_cache(struct io_kiocb * req,struct io_ring_ctx * ctx)239 static inline void io_req_add_to_cache(struct io_kiocb *req, struct io_ring_ctx *ctx)
240 {
241 wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);
242 }
243
io_ring_ctx_ref_free(struct percpu_ref * ref)244 static __cold void io_ring_ctx_ref_free(struct percpu_ref *ref)
245 {
246 struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
247
248 complete(&ctx->ref_comp);
249 }
250
io_fallback_req_func(struct work_struct * work)251 static __cold void io_fallback_req_func(struct work_struct *work)
252 {
253 struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
254 fallback_work.work);
255 struct llist_node *node = llist_del_all(&ctx->fallback_llist);
256 struct io_kiocb *req, *tmp;
257 struct io_tw_state ts = { .locked = true, };
258
259 percpu_ref_get(&ctx->refs);
260 mutex_lock(&ctx->uring_lock);
261 llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
262 req->io_task_work.func(req, &ts);
263 if (WARN_ON_ONCE(!ts.locked))
264 return;
265 io_submit_flush_completions(ctx);
266 mutex_unlock(&ctx->uring_lock);
267 percpu_ref_put(&ctx->refs);
268 }
269
io_alloc_hash_table(struct io_hash_table * table,unsigned bits)270 static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
271 {
272 unsigned hash_buckets = 1U << bits;
273 size_t hash_size = hash_buckets * sizeof(table->hbs[0]);
274
275 table->hbs = kmalloc(hash_size, GFP_KERNEL);
276 if (!table->hbs)
277 return -ENOMEM;
278
279 table->hash_bits = bits;
280 init_hash_table(table, hash_buckets);
281 return 0;
282 }
283
io_ring_ctx_alloc(struct io_uring_params * p)284 static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
285 {
286 struct io_ring_ctx *ctx;
287 int hash_bits;
288
289 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
290 if (!ctx)
291 return NULL;
292
293 xa_init(&ctx->io_bl_xa);
294
295 /*
296 * Use 5 bits less than the max cq entries, that should give us around
297 * 32 entries per hash list if totally full and uniformly spread, but
298 * don't keep too many buckets to not overconsume memory.
299 */
300 hash_bits = ilog2(p->cq_entries) - 5;
301 hash_bits = clamp(hash_bits, 1, 8);
302 if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
303 goto err;
304 if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
305 goto err;
306 if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
307 0, GFP_KERNEL))
308 goto err;
309
310 ctx->flags = p->flags;
311 init_waitqueue_head(&ctx->sqo_sq_wait);
312 INIT_LIST_HEAD(&ctx->sqd_list);
313 INIT_LIST_HEAD(&ctx->cq_overflow_list);
314 INIT_LIST_HEAD(&ctx->io_buffers_cache);
315 INIT_HLIST_HEAD(&ctx->io_buf_list);
316 io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
317 sizeof(struct io_rsrc_node));
318 io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
319 sizeof(struct async_poll));
320 io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
321 sizeof(struct io_async_msghdr));
322 init_completion(&ctx->ref_comp);
323 xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
324 mutex_init(&ctx->uring_lock);
325 init_waitqueue_head(&ctx->cq_wait);
326 init_waitqueue_head(&ctx->poll_wq);
327 init_waitqueue_head(&ctx->rsrc_quiesce_wq);
328 spin_lock_init(&ctx->completion_lock);
329 spin_lock_init(&ctx->timeout_lock);
330 INIT_WQ_LIST(&ctx->iopoll_list);
331 INIT_LIST_HEAD(&ctx->io_buffers_pages);
332 INIT_LIST_HEAD(&ctx->io_buffers_comp);
333 INIT_LIST_HEAD(&ctx->defer_list);
334 INIT_LIST_HEAD(&ctx->timeout_list);
335 INIT_LIST_HEAD(&ctx->ltimeout_list);
336 INIT_LIST_HEAD(&ctx->rsrc_ref_list);
337 init_llist_head(&ctx->work_llist);
338 INIT_LIST_HEAD(&ctx->tctx_list);
339 ctx->submit_state.free_list.next = NULL;
340 INIT_WQ_LIST(&ctx->locked_free_list);
341 INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
342 INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
343 return ctx;
344 err:
345 kfree(ctx->cancel_table.hbs);
346 kfree(ctx->cancel_table_locked.hbs);
347 xa_destroy(&ctx->io_bl_xa);
348 kfree(ctx);
349 return NULL;
350 }
351
io_account_cq_overflow(struct io_ring_ctx * ctx)352 static void io_account_cq_overflow(struct io_ring_ctx *ctx)
353 {
354 struct io_rings *r = ctx->rings;
355
356 WRITE_ONCE(r->cq_overflow, READ_ONCE(r->cq_overflow) + 1);
357 ctx->cq_extra--;
358 }
359
req_need_defer(struct io_kiocb * req,u32 seq)360 static bool req_need_defer(struct io_kiocb *req, u32 seq)
361 {
362 if (unlikely(req->flags & REQ_F_IO_DRAIN)) {
363 struct io_ring_ctx *ctx = req->ctx;
364
365 return seq + READ_ONCE(ctx->cq_extra) != ctx->cached_cq_tail;
366 }
367
368 return false;
369 }
370
io_clean_op(struct io_kiocb * req)371 static void io_clean_op(struct io_kiocb *req)
372 {
373 if (req->flags & REQ_F_BUFFER_SELECTED) {
374 spin_lock(&req->ctx->completion_lock);
375 io_put_kbuf_comp(req);
376 spin_unlock(&req->ctx->completion_lock);
377 }
378
379 if (req->flags & REQ_F_NEED_CLEANUP) {
380 const struct io_cold_def *def = &io_cold_defs[req->opcode];
381
382 if (def->cleanup)
383 def->cleanup(req);
384 }
385 if ((req->flags & REQ_F_POLLED) && req->apoll) {
386 kfree(req->apoll->double_poll);
387 kfree(req->apoll);
388 req->apoll = NULL;
389 }
390 if (req->flags & REQ_F_INFLIGHT) {
391 struct io_uring_task *tctx = req->task->io_uring;
392
393 atomic_dec(&tctx->inflight_tracked);
394 }
395 if (req->flags & REQ_F_CREDS)
396 put_cred(req->creds);
397 if (req->flags & REQ_F_ASYNC_DATA) {
398 kfree(req->async_data);
399 req->async_data = NULL;
400 }
401 req->flags &= ~IO_REQ_CLEAN_FLAGS;
402 }
403
io_req_track_inflight(struct io_kiocb * req)404 static inline void io_req_track_inflight(struct io_kiocb *req)
405 {
406 if (!(req->flags & REQ_F_INFLIGHT)) {
407 req->flags |= REQ_F_INFLIGHT;
408 atomic_inc(&req->task->io_uring->inflight_tracked);
409 }
410 }
411
__io_prep_linked_timeout(struct io_kiocb * req)412 static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
413 {
414 if (WARN_ON_ONCE(!req->link))
415 return NULL;
416
417 req->flags &= ~REQ_F_ARM_LTIMEOUT;
418 req->flags |= REQ_F_LINK_TIMEOUT;
419
420 /* linked timeouts should have two refs once prep'ed */
421 io_req_set_refcount(req);
422 __io_req_set_refcount(req->link, 2);
423 return req->link;
424 }
425
io_prep_linked_timeout(struct io_kiocb * req)426 static inline struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
427 {
428 if (likely(!(req->flags & REQ_F_ARM_LTIMEOUT)))
429 return NULL;
430 return __io_prep_linked_timeout(req);
431 }
432
__io_arm_ltimeout(struct io_kiocb * req)433 static noinline void __io_arm_ltimeout(struct io_kiocb *req)
434 {
435 io_queue_linked_timeout(__io_prep_linked_timeout(req));
436 }
437
io_arm_ltimeout(struct io_kiocb * req)438 static inline void io_arm_ltimeout(struct io_kiocb *req)
439 {
440 if (unlikely(req->flags & REQ_F_ARM_LTIMEOUT))
441 __io_arm_ltimeout(req);
442 }
443
io_prep_async_work(struct io_kiocb * req)444 static void io_prep_async_work(struct io_kiocb *req)
445 {
446 const struct io_issue_def *def = &io_issue_defs[req->opcode];
447 struct io_ring_ctx *ctx = req->ctx;
448
449 if (!(req->flags & REQ_F_CREDS)) {
450 req->flags |= REQ_F_CREDS;
451 req->creds = get_current_cred();
452 }
453
454 req->work.list.next = NULL;
455 req->work.flags = 0;
456 req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
457 if (req->flags & REQ_F_FORCE_ASYNC)
458 req->work.flags |= IO_WQ_WORK_CONCURRENT;
459
460 if (req->file && !(req->flags & REQ_F_FIXED_FILE))
461 req->flags |= io_file_get_flags(req->file);
462
463 if (req->file && (req->flags & REQ_F_ISREG)) {
464 bool should_hash = def->hash_reg_file;
465
466 /* don't serialize this request if the fs doesn't need it */
467 if (should_hash && (req->file->f_flags & O_DIRECT) &&
468 (req->file->f_mode & FMODE_DIO_PARALLEL_WRITE))
469 should_hash = false;
470 if (should_hash || (ctx->flags & IORING_SETUP_IOPOLL))
471 io_wq_hash_work(&req->work, file_inode(req->file));
472 } else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
473 if (def->unbound_nonreg_file)
474 req->work.flags |= IO_WQ_WORK_UNBOUND;
475 }
476 }
477
io_prep_async_link(struct io_kiocb * req)478 static void io_prep_async_link(struct io_kiocb *req)
479 {
480 struct io_kiocb *cur;
481
482 if (req->flags & REQ_F_LINK_TIMEOUT) {
483 struct io_ring_ctx *ctx = req->ctx;
484
485 spin_lock_irq(&ctx->timeout_lock);
486 io_for_each_link(cur, req)
487 io_prep_async_work(cur);
488 spin_unlock_irq(&ctx->timeout_lock);
489 } else {
490 io_for_each_link(cur, req)
491 io_prep_async_work(cur);
492 }
493 }
494
io_queue_iowq(struct io_kiocb * req,struct io_tw_state * ts_dont_use)495 void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use)
496 {
497 struct io_kiocb *link = io_prep_linked_timeout(req);
498 struct io_uring_task *tctx = req->task->io_uring;
499
500 BUG_ON(!tctx);
501 BUG_ON(!tctx->io_wq);
502
503 /* init ->work of the whole link before punting */
504 io_prep_async_link(req);
505
506 /*
507 * Not expected to happen, but if we do have a bug where this _can_
508 * happen, catch it here and ensure the request is marked as
509 * canceled. That will make io-wq go through the usual work cancel
510 * procedure rather than attempt to run this request (or create a new
511 * worker for it).
512 */
513 if (WARN_ON_ONCE(!same_thread_group(req->task, current)))
514 req->work.flags |= IO_WQ_WORK_CANCEL;
515
516 trace_io_uring_queue_async_work(req, io_wq_is_hashed(&req->work));
517 io_wq_enqueue(tctx->io_wq, &req->work);
518 if (link)
519 io_queue_linked_timeout(link);
520 }
521
io_queue_deferred(struct io_ring_ctx * ctx)522 static __cold void io_queue_deferred(struct io_ring_ctx *ctx)
523 {
524 while (!list_empty(&ctx->defer_list)) {
525 struct io_defer_entry *de = list_first_entry(&ctx->defer_list,
526 struct io_defer_entry, list);
527
528 if (req_need_defer(de->req, de->seq))
529 break;
530 list_del_init(&de->list);
531 io_req_task_queue(de->req);
532 kfree(de);
533 }
534 }
535
536
io_eventfd_ops(struct rcu_head * rcu)537 static void io_eventfd_ops(struct rcu_head *rcu)
538 {
539 struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu);
540 int ops = atomic_xchg(&ev_fd->ops, 0);
541
542 if (ops & BIT(IO_EVENTFD_OP_SIGNAL_BIT))
543 eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
544
545 /* IO_EVENTFD_OP_FREE_BIT may not be set here depending on callback
546 * ordering in a race but if references are 0 we know we have to free
547 * it regardless.
548 */
549 if (atomic_dec_and_test(&ev_fd->refs)) {
550 eventfd_ctx_put(ev_fd->cq_ev_fd);
551 kfree(ev_fd);
552 }
553 }
554
io_eventfd_signal(struct io_ring_ctx * ctx)555 static void io_eventfd_signal(struct io_ring_ctx *ctx)
556 {
557 struct io_ev_fd *ev_fd = NULL;
558
559 rcu_read_lock();
560 /*
561 * rcu_dereference ctx->io_ev_fd once and use it for both for checking
562 * and eventfd_signal
563 */
564 ev_fd = rcu_dereference(ctx->io_ev_fd);
565
566 /*
567 * Check again if ev_fd exists incase an io_eventfd_unregister call
568 * completed between the NULL check of ctx->io_ev_fd at the start of
569 * the function and rcu_read_lock.
570 */
571 if (unlikely(!ev_fd))
572 goto out;
573 if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
574 goto out;
575 if (ev_fd->eventfd_async && !io_wq_current_is_worker())
576 goto out;
577
578 if (likely(eventfd_signal_allowed())) {
579 eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
580 } else {
581 atomic_inc(&ev_fd->refs);
582 if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_SIGNAL_BIT), &ev_fd->ops))
583 call_rcu_hurry(&ev_fd->rcu, io_eventfd_ops);
584 else
585 atomic_dec(&ev_fd->refs);
586 }
587
588 out:
589 rcu_read_unlock();
590 }
591
io_eventfd_flush_signal(struct io_ring_ctx * ctx)592 static void io_eventfd_flush_signal(struct io_ring_ctx *ctx)
593 {
594 bool skip;
595
596 spin_lock(&ctx->completion_lock);
597
598 /*
599 * Eventfd should only get triggered when at least one event has been
600 * posted. Some applications rely on the eventfd notification count
601 * only changing IFF a new CQE has been added to the CQ ring. There's
602 * no depedency on 1:1 relationship between how many times this
603 * function is called (and hence the eventfd count) and number of CQEs
604 * posted to the CQ ring.
605 */
606 skip = ctx->cached_cq_tail == ctx->evfd_last_cq_tail;
607 ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
608 spin_unlock(&ctx->completion_lock);
609 if (skip)
610 return;
611
612 io_eventfd_signal(ctx);
613 }
614
__io_commit_cqring_flush(struct io_ring_ctx * ctx)615 void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
616 {
617 if (ctx->poll_activated)
618 io_poll_wq_wake(ctx);
619 if (ctx->off_timeout_used)
620 io_flush_timeouts(ctx);
621 if (ctx->drain_active) {
622 spin_lock(&ctx->completion_lock);
623 io_queue_deferred(ctx);
624 spin_unlock(&ctx->completion_lock);
625 }
626 if (ctx->has_evfd)
627 io_eventfd_flush_signal(ctx);
628 }
629
__io_cq_lock(struct io_ring_ctx * ctx)630 static inline void __io_cq_lock(struct io_ring_ctx *ctx)
631 {
632 if (!ctx->lockless_cq)
633 spin_lock(&ctx->completion_lock);
634 }
635
io_cq_lock(struct io_ring_ctx * ctx)636 static inline void io_cq_lock(struct io_ring_ctx *ctx)
637 __acquires(ctx->completion_lock)
638 {
639 spin_lock(&ctx->completion_lock);
640 }
641
__io_cq_unlock_post(struct io_ring_ctx * ctx)642 static inline void __io_cq_unlock_post(struct io_ring_ctx *ctx)
643 {
644 io_commit_cqring(ctx);
645 if (!ctx->task_complete) {
646 if (!ctx->lockless_cq)
647 spin_unlock(&ctx->completion_lock);
648 /* IOPOLL rings only need to wake up if it's also SQPOLL */
649 if (!ctx->syscall_iopoll)
650 io_cqring_wake(ctx);
651 }
652 io_commit_cqring_flush(ctx);
653 }
654
io_cq_unlock_post(struct io_ring_ctx * ctx)655 static void io_cq_unlock_post(struct io_ring_ctx *ctx)
656 __releases(ctx->completion_lock)
657 {
658 io_commit_cqring(ctx);
659 spin_unlock(&ctx->completion_lock);
660 io_cqring_wake(ctx);
661 io_commit_cqring_flush(ctx);
662 }
663
664 /* Returns true if there are no backlogged entries after the flush */
io_cqring_overflow_kill(struct io_ring_ctx * ctx)665 static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
666 {
667 struct io_overflow_cqe *ocqe;
668 LIST_HEAD(list);
669
670 spin_lock(&ctx->completion_lock);
671 list_splice_init(&ctx->cq_overflow_list, &list);
672 clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
673 spin_unlock(&ctx->completion_lock);
674
675 while (!list_empty(&list)) {
676 ocqe = list_first_entry(&list, struct io_overflow_cqe, list);
677 list_del(&ocqe->list);
678 kfree(ocqe);
679 }
680 }
681
__io_cqring_overflow_flush(struct io_ring_ctx * ctx)682 static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
683 {
684 size_t cqe_size = sizeof(struct io_uring_cqe);
685
686 if (__io_cqring_events(ctx) == ctx->cq_entries)
687 return;
688
689 if (ctx->flags & IORING_SETUP_CQE32)
690 cqe_size <<= 1;
691
692 io_cq_lock(ctx);
693 while (!list_empty(&ctx->cq_overflow_list)) {
694 struct io_uring_cqe *cqe;
695 struct io_overflow_cqe *ocqe;
696
697 if (!io_get_cqe_overflow(ctx, &cqe, true))
698 break;
699 ocqe = list_first_entry(&ctx->cq_overflow_list,
700 struct io_overflow_cqe, list);
701 memcpy(cqe, &ocqe->cqe, cqe_size);
702 list_del(&ocqe->list);
703 kfree(ocqe);
704 }
705
706 if (list_empty(&ctx->cq_overflow_list)) {
707 clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
708 atomic_andnot(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
709 }
710 io_cq_unlock_post(ctx);
711 }
712
io_cqring_do_overflow_flush(struct io_ring_ctx * ctx)713 static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx)
714 {
715 /* iopoll syncs against uring_lock, not completion_lock */
716 if (ctx->flags & IORING_SETUP_IOPOLL)
717 mutex_lock(&ctx->uring_lock);
718 __io_cqring_overflow_flush(ctx);
719 if (ctx->flags & IORING_SETUP_IOPOLL)
720 mutex_unlock(&ctx->uring_lock);
721 }
722
io_cqring_overflow_flush(struct io_ring_ctx * ctx)723 static void io_cqring_overflow_flush(struct io_ring_ctx *ctx)
724 {
725 if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
726 io_cqring_do_overflow_flush(ctx);
727 }
728
729 /* can be called by any task */
io_put_task_remote(struct task_struct * task)730 static void io_put_task_remote(struct task_struct *task)
731 {
732 struct io_uring_task *tctx = task->io_uring;
733
734 percpu_counter_sub(&tctx->inflight, 1);
735 if (unlikely(atomic_read(&tctx->in_cancel)))
736 wake_up(&tctx->wait);
737 put_task_struct(task);
738 }
739
740 /* used by a task to put its own references */
io_put_task_local(struct task_struct * task)741 static void io_put_task_local(struct task_struct *task)
742 {
743 task->io_uring->cached_refs++;
744 }
745
746 /* must to be called somewhat shortly after putting a request */
io_put_task(struct task_struct * task)747 static inline void io_put_task(struct task_struct *task)
748 {
749 if (likely(task == current))
750 io_put_task_local(task);
751 else
752 io_put_task_remote(task);
753 }
754
io_task_refs_refill(struct io_uring_task * tctx)755 void io_task_refs_refill(struct io_uring_task *tctx)
756 {
757 unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR;
758
759 percpu_counter_add(&tctx->inflight, refill);
760 refcount_add(refill, ¤t->usage);
761 tctx->cached_refs += refill;
762 }
763
io_uring_drop_tctx_refs(struct task_struct * task)764 static __cold void io_uring_drop_tctx_refs(struct task_struct *task)
765 {
766 struct io_uring_task *tctx = task->io_uring;
767 unsigned int refs = tctx->cached_refs;
768
769 if (refs) {
770 tctx->cached_refs = 0;
771 percpu_counter_sub(&tctx->inflight, refs);
772 put_task_struct_many(task, refs);
773 }
774 }
775
io_cqring_event_overflow(struct io_ring_ctx * ctx,u64 user_data,s32 res,u32 cflags,u64 extra1,u64 extra2)776 static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
777 s32 res, u32 cflags, u64 extra1, u64 extra2)
778 {
779 struct io_overflow_cqe *ocqe;
780 size_t ocq_size = sizeof(struct io_overflow_cqe);
781 bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
782
783 lockdep_assert_held(&ctx->completion_lock);
784
785 if (is_cqe32)
786 ocq_size += sizeof(struct io_uring_cqe);
787
788 ocqe = kmalloc(ocq_size, GFP_ATOMIC | __GFP_ACCOUNT);
789 trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
790 if (!ocqe) {
791 /*
792 * If we're in ring overflow flush mode, or in task cancel mode,
793 * or cannot allocate an overflow entry, then we need to drop it
794 * on the floor.
795 */
796 io_account_cq_overflow(ctx);
797 set_bit(IO_CHECK_CQ_DROPPED_BIT, &ctx->check_cq);
798 return false;
799 }
800 if (list_empty(&ctx->cq_overflow_list)) {
801 set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
802 atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
803
804 }
805 ocqe->cqe.user_data = user_data;
806 ocqe->cqe.res = res;
807 ocqe->cqe.flags = cflags;
808 if (is_cqe32) {
809 ocqe->cqe.big_cqe[0] = extra1;
810 ocqe->cqe.big_cqe[1] = extra2;
811 }
812 list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
813 return true;
814 }
815
io_req_cqe_overflow(struct io_kiocb * req)816 void io_req_cqe_overflow(struct io_kiocb *req)
817 {
818 io_cqring_event_overflow(req->ctx, req->cqe.user_data,
819 req->cqe.res, req->cqe.flags,
820 req->big_cqe.extra1, req->big_cqe.extra2);
821 memset(&req->big_cqe, 0, sizeof(req->big_cqe));
822 }
823
824 /*
825 * writes to the cq entry need to come after reading head; the
826 * control dependency is enough as we're using WRITE_ONCE to
827 * fill the cq entry
828 */
io_cqe_cache_refill(struct io_ring_ctx * ctx,bool overflow)829 bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow)
830 {
831 struct io_rings *rings = ctx->rings;
832 unsigned int off = ctx->cached_cq_tail & (ctx->cq_entries - 1);
833 unsigned int free, queued, len;
834
835 /*
836 * Posting into the CQ when there are pending overflowed CQEs may break
837 * ordering guarantees, which will affect links, F_MORE users and more.
838 * Force overflow the completion.
839 */
840 if (!overflow && (ctx->check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT)))
841 return false;
842
843 /* userspace may cheat modifying the tail, be safe and do min */
844 queued = min(__io_cqring_events(ctx), ctx->cq_entries);
845 free = ctx->cq_entries - queued;
846 /* we need a contiguous range, limit based on the current array offset */
847 len = min(free, ctx->cq_entries - off);
848 if (!len)
849 return false;
850
851 if (ctx->flags & IORING_SETUP_CQE32) {
852 off <<= 1;
853 len <<= 1;
854 }
855
856 ctx->cqe_cached = &rings->cqes[off];
857 ctx->cqe_sentinel = ctx->cqe_cached + len;
858 return true;
859 }
860
io_fill_cqe_aux(struct io_ring_ctx * ctx,u64 user_data,s32 res,u32 cflags)861 static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res,
862 u32 cflags)
863 {
864 struct io_uring_cqe *cqe;
865
866 ctx->cq_extra++;
867
868 /*
869 * If we can't get a cq entry, userspace overflowed the
870 * submission (by quite a lot). Increment the overflow count in
871 * the ring.
872 */
873 if (likely(io_get_cqe(ctx, &cqe))) {
874 trace_io_uring_complete(ctx, NULL, user_data, res, cflags, 0, 0);
875
876 WRITE_ONCE(cqe->user_data, user_data);
877 WRITE_ONCE(cqe->res, res);
878 WRITE_ONCE(cqe->flags, cflags);
879
880 if (ctx->flags & IORING_SETUP_CQE32) {
881 WRITE_ONCE(cqe->big_cqe[0], 0);
882 WRITE_ONCE(cqe->big_cqe[1], 0);
883 }
884 return true;
885 }
886 return false;
887 }
888
__io_flush_post_cqes(struct io_ring_ctx * ctx)889 static void __io_flush_post_cqes(struct io_ring_ctx *ctx)
890 __must_hold(&ctx->uring_lock)
891 {
892 struct io_submit_state *state = &ctx->submit_state;
893 unsigned int i;
894
895 lockdep_assert_held(&ctx->uring_lock);
896 for (i = 0; i < state->cqes_count; i++) {
897 struct io_uring_cqe *cqe = &ctx->completion_cqes[i];
898
899 if (!io_fill_cqe_aux(ctx, cqe->user_data, cqe->res, cqe->flags)) {
900 if (ctx->lockless_cq) {
901 spin_lock(&ctx->completion_lock);
902 io_cqring_event_overflow(ctx, cqe->user_data,
903 cqe->res, cqe->flags, 0, 0);
904 spin_unlock(&ctx->completion_lock);
905 } else {
906 io_cqring_event_overflow(ctx, cqe->user_data,
907 cqe->res, cqe->flags, 0, 0);
908 }
909 }
910 }
911 state->cqes_count = 0;
912 }
913
__io_post_aux_cqe(struct io_ring_ctx * ctx,u64 user_data,s32 res,u32 cflags,bool allow_overflow)914 static bool __io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags,
915 bool allow_overflow)
916 {
917 bool filled;
918
919 io_cq_lock(ctx);
920 filled = io_fill_cqe_aux(ctx, user_data, res, cflags);
921 if (!filled && allow_overflow)
922 filled = io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
923
924 io_cq_unlock_post(ctx);
925 return filled;
926 }
927
io_post_aux_cqe(struct io_ring_ctx * ctx,u64 user_data,s32 res,u32 cflags)928 bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
929 {
930 return __io_post_aux_cqe(ctx, user_data, res, cflags, true);
931 }
932
933 /*
934 * A helper for multishot requests posting additional CQEs.
935 * Should only be used from a task_work including IO_URING_F_MULTISHOT.
936 */
io_fill_cqe_req_aux(struct io_kiocb * req,bool defer,s32 res,u32 cflags)937 bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags)
938 {
939 struct io_ring_ctx *ctx = req->ctx;
940 u64 user_data = req->cqe.user_data;
941 struct io_uring_cqe *cqe;
942
943 if (!defer)
944 return __io_post_aux_cqe(ctx, user_data, res, cflags, false);
945
946 lockdep_assert_held(&ctx->uring_lock);
947
948 if (ctx->submit_state.cqes_count == ARRAY_SIZE(ctx->completion_cqes)) {
949 __io_cq_lock(ctx);
950 __io_flush_post_cqes(ctx);
951 /* no need to flush - flush is deferred */
952 __io_cq_unlock_post(ctx);
953 }
954
955 /* For defered completions this is not as strict as it is otherwise,
956 * however it's main job is to prevent unbounded posted completions,
957 * and in that it works just as well.
958 */
959 if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
960 return false;
961
962 cqe = &ctx->completion_cqes[ctx->submit_state.cqes_count++];
963 cqe->user_data = user_data;
964 cqe->res = res;
965 cqe->flags = cflags;
966 return true;
967 }
968
__io_req_complete_post(struct io_kiocb * req,unsigned issue_flags)969 static void __io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
970 {
971 struct io_ring_ctx *ctx = req->ctx;
972 struct io_rsrc_node *rsrc_node = NULL;
973
974 io_cq_lock(ctx);
975 if (!(req->flags & REQ_F_CQE_SKIP)) {
976 if (!io_fill_cqe_req(ctx, req))
977 io_req_cqe_overflow(req);
978 }
979
980 /*
981 * If we're the last reference to this request, add to our locked
982 * free_list cache.
983 */
984 if (req_ref_put_and_test(req)) {
985 if (req->flags & IO_REQ_LINK_FLAGS) {
986 if (req->flags & IO_DISARM_MASK)
987 io_disarm_next(req);
988 if (req->link) {
989 io_req_task_queue(req->link);
990 req->link = NULL;
991 }
992 }
993 io_put_kbuf_comp(req);
994 if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
995 io_clean_op(req);
996 io_put_file(req);
997
998 rsrc_node = req->rsrc_node;
999 /*
1000 * Selected buffer deallocation in io_clean_op() assumes that
1001 * we don't hold ->completion_lock. Clean them here to avoid
1002 * deadlocks.
1003 */
1004 io_put_task_remote(req->task);
1005 wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
1006 ctx->locked_free_nr++;
1007 }
1008 io_cq_unlock_post(ctx);
1009
1010 if (rsrc_node) {
1011 io_ring_submit_lock(ctx, issue_flags);
1012 io_put_rsrc_node(ctx, rsrc_node);
1013 io_ring_submit_unlock(ctx, issue_flags);
1014 }
1015 }
1016
io_req_complete_post(struct io_kiocb * req,unsigned issue_flags)1017 void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
1018 {
1019 if (req->ctx->task_complete && req->ctx->submitter_task != current) {
1020 req->io_task_work.func = io_req_task_complete;
1021 io_req_task_work_add(req);
1022 } else if (!(issue_flags & IO_URING_F_UNLOCKED) ||
1023 !(req->ctx->flags & IORING_SETUP_IOPOLL)) {
1024 __io_req_complete_post(req, issue_flags);
1025 } else {
1026 struct io_ring_ctx *ctx = req->ctx;
1027
1028 mutex_lock(&ctx->uring_lock);
1029 __io_req_complete_post(req, issue_flags & ~IO_URING_F_UNLOCKED);
1030 mutex_unlock(&ctx->uring_lock);
1031 }
1032 }
1033
io_req_defer_failed(struct io_kiocb * req,s32 res)1034 void io_req_defer_failed(struct io_kiocb *req, s32 res)
1035 __must_hold(&ctx->uring_lock)
1036 {
1037 const struct io_cold_def *def = &io_cold_defs[req->opcode];
1038
1039 lockdep_assert_held(&req->ctx->uring_lock);
1040
1041 req_set_fail(req);
1042 io_req_set_res(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
1043 if (def->fail)
1044 def->fail(req);
1045 io_req_complete_defer(req);
1046 }
1047
1048 /*
1049 * Don't initialise the fields below on every allocation, but do that in
1050 * advance and keep them valid across allocations.
1051 */
io_preinit_req(struct io_kiocb * req,struct io_ring_ctx * ctx)1052 static void io_preinit_req(struct io_kiocb *req, struct io_ring_ctx *ctx)
1053 {
1054 req->ctx = ctx;
1055 req->link = NULL;
1056 req->async_data = NULL;
1057 /* not necessary, but safer to zero */
1058 memset(&req->cqe, 0, sizeof(req->cqe));
1059 memset(&req->big_cqe, 0, sizeof(req->big_cqe));
1060 }
1061
io_flush_cached_locked_reqs(struct io_ring_ctx * ctx,struct io_submit_state * state)1062 static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
1063 struct io_submit_state *state)
1064 {
1065 spin_lock(&ctx->completion_lock);
1066 wq_list_splice(&ctx->locked_free_list, &state->free_list);
1067 ctx->locked_free_nr = 0;
1068 spin_unlock(&ctx->completion_lock);
1069 }
1070
1071 /*
1072 * A request might get retired back into the request caches even before opcode
1073 * handlers and io_issue_sqe() are done with it, e.g. inline completion path.
1074 * Because of that, io_alloc_req() should be called only under ->uring_lock
1075 * and with extra caution to not get a request that is still worked on.
1076 */
__io_alloc_req_refill(struct io_ring_ctx * ctx)1077 __cold bool __io_alloc_req_refill(struct io_ring_ctx *ctx)
1078 __must_hold(&ctx->uring_lock)
1079 {
1080 gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
1081 void *reqs[IO_REQ_ALLOC_BATCH];
1082 int ret, i;
1083
1084 /*
1085 * If we have more than a batch's worth of requests in our IRQ side
1086 * locked cache, grab the lock and move them over to our submission
1087 * side cache.
1088 */
1089 if (data_race(ctx->locked_free_nr) > IO_COMPL_BATCH) {
1090 io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
1091 if (!io_req_cache_empty(ctx))
1092 return true;
1093 }
1094
1095 ret = kmem_cache_alloc_bulk(req_cachep, gfp, ARRAY_SIZE(reqs), reqs);
1096
1097 /*
1098 * Bulk alloc is all-or-nothing. If we fail to get a batch,
1099 * retry single alloc to be on the safe side.
1100 */
1101 if (unlikely(ret <= 0)) {
1102 reqs[0] = kmem_cache_alloc(req_cachep, gfp);
1103 if (!reqs[0])
1104 return false;
1105 ret = 1;
1106 }
1107
1108 percpu_ref_get_many(&ctx->refs, ret);
1109 for (i = 0; i < ret; i++) {
1110 struct io_kiocb *req = reqs[i];
1111
1112 io_preinit_req(req, ctx);
1113 io_req_add_to_cache(req, ctx);
1114 }
1115 return true;
1116 }
1117
io_free_req(struct io_kiocb * req)1118 __cold void io_free_req(struct io_kiocb *req)
1119 {
1120 /* refs were already put, restore them for io_req_task_complete() */
1121 req->flags &= ~REQ_F_REFCOUNT;
1122 /* we only want to free it, don't post CQEs */
1123 req->flags |= REQ_F_CQE_SKIP;
1124 req->io_task_work.func = io_req_task_complete;
1125 io_req_task_work_add(req);
1126 }
1127
__io_req_find_next_prep(struct io_kiocb * req)1128 static void __io_req_find_next_prep(struct io_kiocb *req)
1129 {
1130 struct io_ring_ctx *ctx = req->ctx;
1131
1132 spin_lock(&ctx->completion_lock);
1133 io_disarm_next(req);
1134 spin_unlock(&ctx->completion_lock);
1135 }
1136
io_req_find_next(struct io_kiocb * req)1137 static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
1138 {
1139 struct io_kiocb *nxt;
1140
1141 /*
1142 * If LINK is set, we have dependent requests in this chain. If we
1143 * didn't fail this request, queue the first one up, moving any other
1144 * dependencies to the next request. In case of failure, fail the rest
1145 * of the chain.
1146 */
1147 if (unlikely(req->flags & IO_DISARM_MASK))
1148 __io_req_find_next_prep(req);
1149 nxt = req->link;
1150 req->link = NULL;
1151 return nxt;
1152 }
1153
ctx_flush_and_put(struct io_ring_ctx * ctx,struct io_tw_state * ts)1154 static void ctx_flush_and_put(struct io_ring_ctx *ctx, struct io_tw_state *ts)
1155 {
1156 if (!ctx)
1157 return;
1158 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
1159 atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
1160 if (ts->locked) {
1161 io_submit_flush_completions(ctx);
1162 mutex_unlock(&ctx->uring_lock);
1163 ts->locked = false;
1164 }
1165 percpu_ref_put(&ctx->refs);
1166 }
1167
handle_tw_list(struct llist_node * node,struct io_ring_ctx ** ctx,struct io_tw_state * ts)1168 static unsigned int handle_tw_list(struct llist_node *node,
1169 struct io_ring_ctx **ctx,
1170 struct io_tw_state *ts)
1171 {
1172 unsigned int count = 0;
1173
1174 do {
1175 struct llist_node *next = node->next;
1176 struct io_kiocb *req = container_of(node, struct io_kiocb,
1177 io_task_work.node);
1178
1179 prefetch(container_of(next, struct io_kiocb, io_task_work.node));
1180
1181 if (req->ctx != *ctx) {
1182 ctx_flush_and_put(*ctx, ts);
1183 *ctx = req->ctx;
1184 /* if not contended, grab and improve batching */
1185 ts->locked = mutex_trylock(&(*ctx)->uring_lock);
1186 percpu_ref_get(&(*ctx)->refs);
1187 }
1188 INDIRECT_CALL_2(req->io_task_work.func,
1189 io_poll_task_func, io_req_rw_complete,
1190 req, ts);
1191 node = next;
1192 count++;
1193 if (unlikely(need_resched())) {
1194 ctx_flush_and_put(*ctx, ts);
1195 *ctx = NULL;
1196 cond_resched();
1197 }
1198 } while (node);
1199
1200 return count;
1201 }
1202
1203 /**
1204 * io_llist_xchg - swap all entries in a lock-less list
1205 * @head: the head of lock-less list to delete all entries
1206 * @new: new entry as the head of the list
1207 *
1208 * If list is empty, return NULL, otherwise, return the pointer to the first entry.
1209 * The order of entries returned is from the newest to the oldest added one.
1210 */
io_llist_xchg(struct llist_head * head,struct llist_node * new)1211 static inline struct llist_node *io_llist_xchg(struct llist_head *head,
1212 struct llist_node *new)
1213 {
1214 return xchg(&head->first, new);
1215 }
1216
io_fallback_tw(struct io_uring_task * tctx,bool sync)1217 static __cold void io_fallback_tw(struct io_uring_task *tctx, bool sync)
1218 {
1219 struct llist_node *node = llist_del_all(&tctx->task_list);
1220 struct io_ring_ctx *last_ctx = NULL;
1221 struct io_kiocb *req;
1222
1223 while (node) {
1224 req = container_of(node, struct io_kiocb, io_task_work.node);
1225 node = node->next;
1226 if (sync && last_ctx != req->ctx) {
1227 if (last_ctx) {
1228 flush_delayed_work(&last_ctx->fallback_work);
1229 percpu_ref_put(&last_ctx->refs);
1230 }
1231 last_ctx = req->ctx;
1232 percpu_ref_get(&last_ctx->refs);
1233 }
1234 if (llist_add(&req->io_task_work.node,
1235 &req->ctx->fallback_llist))
1236 schedule_delayed_work(&req->ctx->fallback_work, 1);
1237 }
1238
1239 if (last_ctx) {
1240 flush_delayed_work(&last_ctx->fallback_work);
1241 percpu_ref_put(&last_ctx->refs);
1242 }
1243 }
1244
tctx_task_work(struct callback_head * cb)1245 void tctx_task_work(struct callback_head *cb)
1246 {
1247 struct io_tw_state ts = {};
1248 struct io_ring_ctx *ctx = NULL;
1249 struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
1250 task_work);
1251 struct llist_node *node;
1252 unsigned int count = 0;
1253
1254 if (unlikely(current->flags & PF_EXITING)) {
1255 io_fallback_tw(tctx, true);
1256 return;
1257 }
1258
1259 node = llist_del_all(&tctx->task_list);
1260 if (node)
1261 count = handle_tw_list(node, &ctx, &ts);
1262
1263 ctx_flush_and_put(ctx, &ts);
1264
1265 /* relaxed read is enough as only the task itself sets ->in_cancel */
1266 if (unlikely(atomic_read(&tctx->in_cancel)))
1267 io_uring_drop_tctx_refs(current);
1268
1269 trace_io_uring_task_work_run(tctx, count, 1);
1270 }
1271
io_req_local_work_add(struct io_kiocb * req,unsigned flags)1272 static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
1273 {
1274 struct io_ring_ctx *ctx = req->ctx;
1275 unsigned nr_wait, nr_tw, nr_tw_prev;
1276 struct llist_node *first;
1277
1278 if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK))
1279 flags &= ~IOU_F_TWQ_LAZY_WAKE;
1280
1281 first = READ_ONCE(ctx->work_llist.first);
1282 do {
1283 nr_tw_prev = 0;
1284 if (first) {
1285 struct io_kiocb *first_req = container_of(first,
1286 struct io_kiocb,
1287 io_task_work.node);
1288 /*
1289 * Might be executed at any moment, rely on
1290 * SLAB_TYPESAFE_BY_RCU to keep it alive.
1291 */
1292 nr_tw_prev = READ_ONCE(first_req->nr_tw);
1293 }
1294 nr_tw = nr_tw_prev + 1;
1295 /* Large enough to fail the nr_wait comparison below */
1296 if (!(flags & IOU_F_TWQ_LAZY_WAKE))
1297 nr_tw = INT_MAX;
1298
1299 req->nr_tw = nr_tw;
1300 req->io_task_work.node.next = first;
1301 } while (!try_cmpxchg(&ctx->work_llist.first, &first,
1302 &req->io_task_work.node));
1303
1304 if (!first) {
1305 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
1306 atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
1307 if (ctx->has_evfd)
1308 io_eventfd_signal(ctx);
1309 }
1310
1311 nr_wait = atomic_read(&ctx->cq_wait_nr);
1312 /* no one is waiting */
1313 if (!nr_wait)
1314 return;
1315 /* either not enough or the previous add has already woken it up */
1316 if (nr_wait > nr_tw || nr_tw_prev >= nr_wait)
1317 return;
1318 /* pairs with set_current_state() in io_cqring_wait() */
1319 smp_mb__after_atomic();
1320 wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
1321 }
1322
io_req_normal_work_add(struct io_kiocb * req)1323 static void io_req_normal_work_add(struct io_kiocb *req)
1324 {
1325 struct io_uring_task *tctx = req->task->io_uring;
1326 struct io_ring_ctx *ctx = req->ctx;
1327
1328 /* task_work already pending, we're done */
1329 if (!llist_add(&req->io_task_work.node, &tctx->task_list))
1330 return;
1331
1332 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
1333 atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
1334
1335 if (likely(!task_work_add(req->task, &tctx->task_work, ctx->notify_method)))
1336 return;
1337
1338 io_fallback_tw(tctx, false);
1339 }
1340
__io_req_task_work_add(struct io_kiocb * req,unsigned flags)1341 void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
1342 {
1343 if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
1344 rcu_read_lock();
1345 io_req_local_work_add(req, flags);
1346 rcu_read_unlock();
1347 } else {
1348 io_req_normal_work_add(req);
1349 }
1350 }
1351
io_move_task_work_from_local(struct io_ring_ctx * ctx)1352 static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
1353 {
1354 struct llist_node *node;
1355
1356 node = llist_del_all(&ctx->work_llist);
1357 while (node) {
1358 struct io_kiocb *req = container_of(node, struct io_kiocb,
1359 io_task_work.node);
1360
1361 node = node->next;
1362 io_req_normal_work_add(req);
1363 }
1364 }
1365
io_run_local_work_continue(struct io_ring_ctx * ctx,int events,int min_events)1366 static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events,
1367 int min_events)
1368 {
1369 if (llist_empty(&ctx->work_llist))
1370 return false;
1371 if (events < min_events)
1372 return true;
1373 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
1374 atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
1375 return false;
1376 }
1377
__io_run_local_work(struct io_ring_ctx * ctx,struct io_tw_state * ts,int min_events)1378 static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts,
1379 int min_events)
1380 {
1381 struct llist_node *node;
1382 unsigned int loops = 0;
1383 int ret = 0;
1384
1385 if (WARN_ON_ONCE(ctx->submitter_task != current))
1386 return -EEXIST;
1387 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
1388 atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
1389 again:
1390 /*
1391 * llists are in reverse order, flip it back the right way before
1392 * running the pending items.
1393 */
1394 node = llist_reverse_order(io_llist_xchg(&ctx->work_llist, NULL));
1395 while (node) {
1396 struct llist_node *next = node->next;
1397 struct io_kiocb *req = container_of(node, struct io_kiocb,
1398 io_task_work.node);
1399 prefetch(container_of(next, struct io_kiocb, io_task_work.node));
1400 INDIRECT_CALL_2(req->io_task_work.func,
1401 io_poll_task_func, io_req_rw_complete,
1402 req, ts);
1403 ret++;
1404 node = next;
1405 }
1406 loops++;
1407
1408 if (io_run_local_work_continue(ctx, ret, min_events))
1409 goto again;
1410 if (ts->locked) {
1411 io_submit_flush_completions(ctx);
1412 if (io_run_local_work_continue(ctx, ret, min_events))
1413 goto again;
1414 }
1415
1416 trace_io_uring_local_work_run(ctx, ret, loops);
1417 return ret;
1418 }
1419
io_run_local_work_locked(struct io_ring_ctx * ctx,int min_events)1420 static inline int io_run_local_work_locked(struct io_ring_ctx *ctx,
1421 int min_events)
1422 {
1423 struct io_tw_state ts = { .locked = true, };
1424 int ret;
1425
1426 if (llist_empty(&ctx->work_llist))
1427 return 0;
1428
1429 ret = __io_run_local_work(ctx, &ts, min_events);
1430 /* shouldn't happen! */
1431 if (WARN_ON_ONCE(!ts.locked))
1432 mutex_lock(&ctx->uring_lock);
1433 return ret;
1434 }
1435
io_run_local_work(struct io_ring_ctx * ctx,int min_events)1436 static int io_run_local_work(struct io_ring_ctx *ctx, int min_events)
1437 {
1438 struct io_tw_state ts = {};
1439 int ret;
1440
1441 ts.locked = mutex_trylock(&ctx->uring_lock);
1442 ret = __io_run_local_work(ctx, &ts, min_events);
1443 if (ts.locked)
1444 mutex_unlock(&ctx->uring_lock);
1445
1446 return ret;
1447 }
1448
io_req_task_cancel(struct io_kiocb * req,struct io_tw_state * ts)1449 static void io_req_task_cancel(struct io_kiocb *req, struct io_tw_state *ts)
1450 {
1451 io_tw_lock(req->ctx, ts);
1452 io_req_defer_failed(req, req->cqe.res);
1453 }
1454
io_req_task_submit(struct io_kiocb * req,struct io_tw_state * ts)1455 void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts)
1456 {
1457 io_tw_lock(req->ctx, ts);
1458 /* req->task == current here, checking PF_EXITING is safe */
1459 if (unlikely(req->task->flags & PF_EXITING))
1460 io_req_defer_failed(req, -EFAULT);
1461 else if (req->flags & REQ_F_FORCE_ASYNC)
1462 io_queue_iowq(req, ts);
1463 else
1464 io_queue_sqe(req);
1465 }
1466
io_req_task_queue_fail(struct io_kiocb * req,int ret)1467 void io_req_task_queue_fail(struct io_kiocb *req, int ret)
1468 {
1469 io_req_set_res(req, ret, 0);
1470 req->io_task_work.func = io_req_task_cancel;
1471 io_req_task_work_add(req);
1472 }
1473
io_req_task_queue(struct io_kiocb * req)1474 void io_req_task_queue(struct io_kiocb *req)
1475 {
1476 req->io_task_work.func = io_req_task_submit;
1477 io_req_task_work_add(req);
1478 }
1479
io_queue_next(struct io_kiocb * req)1480 void io_queue_next(struct io_kiocb *req)
1481 {
1482 struct io_kiocb *nxt = io_req_find_next(req);
1483
1484 if (nxt)
1485 io_req_task_queue(nxt);
1486 }
1487
io_free_batch_list(struct io_ring_ctx * ctx,struct io_wq_work_node * node)1488 static void io_free_batch_list(struct io_ring_ctx *ctx,
1489 struct io_wq_work_node *node)
1490 __must_hold(&ctx->uring_lock)
1491 {
1492 do {
1493 struct io_kiocb *req = container_of(node, struct io_kiocb,
1494 comp_list);
1495
1496 if (unlikely(req->flags & IO_REQ_CLEAN_SLOW_FLAGS)) {
1497 if (req->flags & REQ_F_REFCOUNT) {
1498 node = req->comp_list.next;
1499 if (!req_ref_put_and_test(req))
1500 continue;
1501 }
1502 if ((req->flags & REQ_F_POLLED) && req->apoll) {
1503 struct async_poll *apoll = req->apoll;
1504
1505 if (apoll->double_poll)
1506 kfree(apoll->double_poll);
1507 if (!io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache))
1508 kfree(apoll);
1509 req->flags &= ~REQ_F_POLLED;
1510 }
1511 if (req->flags & IO_REQ_LINK_FLAGS)
1512 io_queue_next(req);
1513 if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
1514 io_clean_op(req);
1515 }
1516 io_put_file(req);
1517
1518 io_req_put_rsrc_locked(req, ctx);
1519
1520 io_put_task(req->task);
1521 node = req->comp_list.next;
1522 io_req_add_to_cache(req, ctx);
1523 } while (node);
1524 }
1525
__io_submit_flush_completions(struct io_ring_ctx * ctx)1526 void __io_submit_flush_completions(struct io_ring_ctx *ctx)
1527 __must_hold(&ctx->uring_lock)
1528 {
1529 struct io_submit_state *state = &ctx->submit_state;
1530 struct io_wq_work_node *node;
1531
1532 __io_cq_lock(ctx);
1533 /* must come first to preserve CQE ordering in failure cases */
1534 if (state->cqes_count)
1535 __io_flush_post_cqes(ctx);
1536 __wq_list_for_each(node, &state->compl_reqs) {
1537 struct io_kiocb *req = container_of(node, struct io_kiocb,
1538 comp_list);
1539
1540 if (!(req->flags & REQ_F_CQE_SKIP) &&
1541 unlikely(!io_fill_cqe_req(ctx, req))) {
1542 if (ctx->lockless_cq) {
1543 spin_lock(&ctx->completion_lock);
1544 io_req_cqe_overflow(req);
1545 spin_unlock(&ctx->completion_lock);
1546 } else {
1547 io_req_cqe_overflow(req);
1548 }
1549 }
1550 }
1551 __io_cq_unlock_post(ctx);
1552
1553 if (!wq_list_empty(&ctx->submit_state.compl_reqs)) {
1554 io_free_batch_list(ctx, state->compl_reqs.first);
1555 INIT_WQ_LIST(&state->compl_reqs);
1556 }
1557 }
1558
io_cqring_events(struct io_ring_ctx * ctx)1559 static unsigned io_cqring_events(struct io_ring_ctx *ctx)
1560 {
1561 /* See comment at the top of this file */
1562 smp_rmb();
1563 return __io_cqring_events(ctx);
1564 }
1565
1566 /*
1567 * We can't just wait for polled events to come to us, we have to actively
1568 * find and complete them.
1569 */
io_iopoll_try_reap_events(struct io_ring_ctx * ctx)1570 static __cold void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
1571 {
1572 if (!(ctx->flags & IORING_SETUP_IOPOLL))
1573 return;
1574
1575 mutex_lock(&ctx->uring_lock);
1576 while (!wq_list_empty(&ctx->iopoll_list)) {
1577 /* let it sleep and repeat later if can't complete a request */
1578 if (io_do_iopoll(ctx, true) == 0)
1579 break;
1580 /*
1581 * Ensure we allow local-to-the-cpu processing to take place,
1582 * in this case we need to ensure that we reap all events.
1583 * Also let task_work, etc. to progress by releasing the mutex
1584 */
1585 if (need_resched()) {
1586 mutex_unlock(&ctx->uring_lock);
1587 cond_resched();
1588 mutex_lock(&ctx->uring_lock);
1589 }
1590 }
1591 mutex_unlock(&ctx->uring_lock);
1592 }
1593
io_iopoll_check(struct io_ring_ctx * ctx,long min)1594 static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
1595 {
1596 unsigned int nr_events = 0;
1597 unsigned long check_cq;
1598
1599 if (!io_allowed_run_tw(ctx))
1600 return -EEXIST;
1601
1602 check_cq = READ_ONCE(ctx->check_cq);
1603 if (unlikely(check_cq)) {
1604 if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
1605 __io_cqring_overflow_flush(ctx);
1606 /*
1607 * Similarly do not spin if we have not informed the user of any
1608 * dropped CQE.
1609 */
1610 if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
1611 return -EBADR;
1612 }
1613 /*
1614 * Don't enter poll loop if we already have events pending.
1615 * If we do, we can potentially be spinning for commands that
1616 * already triggered a CQE (eg in error).
1617 */
1618 if (io_cqring_events(ctx))
1619 return 0;
1620
1621 do {
1622 int ret = 0;
1623
1624 /*
1625 * If a submit got punted to a workqueue, we can have the
1626 * application entering polling for a command before it gets
1627 * issued. That app will hold the uring_lock for the duration
1628 * of the poll right here, so we need to take a breather every
1629 * now and then to ensure that the issue has a chance to add
1630 * the poll to the issued list. Otherwise we can spin here
1631 * forever, while the workqueue is stuck trying to acquire the
1632 * very same mutex.
1633 */
1634 if (wq_list_empty(&ctx->iopoll_list) ||
1635 io_task_work_pending(ctx)) {
1636 u32 tail = ctx->cached_cq_tail;
1637
1638 (void) io_run_local_work_locked(ctx, min);
1639
1640 if (task_work_pending(current) ||
1641 wq_list_empty(&ctx->iopoll_list)) {
1642 mutex_unlock(&ctx->uring_lock);
1643 io_run_task_work();
1644 mutex_lock(&ctx->uring_lock);
1645 }
1646 /* some requests don't go through iopoll_list */
1647 if (tail != ctx->cached_cq_tail ||
1648 wq_list_empty(&ctx->iopoll_list))
1649 break;
1650 }
1651 ret = io_do_iopoll(ctx, !min);
1652 if (unlikely(ret < 0))
1653 return ret;
1654
1655 if (task_sigpending(current))
1656 return -EINTR;
1657 if (need_resched())
1658 break;
1659
1660 nr_events += ret;
1661 } while (nr_events < min);
1662
1663 return 0;
1664 }
1665
io_req_task_complete(struct io_kiocb * req,struct io_tw_state * ts)1666 void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts)
1667 {
1668 if (ts->locked)
1669 io_req_complete_defer(req);
1670 else
1671 io_req_complete_post(req, IO_URING_F_UNLOCKED);
1672 }
1673
1674 /*
1675 * After the iocb has been issued, it's safe to be found on the poll list.
1676 * Adding the kiocb to the list AFTER submission ensures that we don't
1677 * find it from a io_do_iopoll() thread before the issuer is done
1678 * accessing the kiocb cookie.
1679 */
io_iopoll_req_issued(struct io_kiocb * req,unsigned int issue_flags)1680 static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
1681 {
1682 struct io_ring_ctx *ctx = req->ctx;
1683 const bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
1684
1685 /* workqueue context doesn't hold uring_lock, grab it now */
1686 if (unlikely(needs_lock))
1687 mutex_lock(&ctx->uring_lock);
1688
1689 /*
1690 * Track whether we have multiple files in our lists. This will impact
1691 * how we do polling eventually, not spinning if we're on potentially
1692 * different devices.
1693 */
1694 if (wq_list_empty(&ctx->iopoll_list)) {
1695 ctx->poll_multi_queue = false;
1696 } else if (!ctx->poll_multi_queue) {
1697 struct io_kiocb *list_req;
1698
1699 list_req = container_of(ctx->iopoll_list.first, struct io_kiocb,
1700 comp_list);
1701 if (list_req->file != req->file)
1702 ctx->poll_multi_queue = true;
1703 }
1704
1705 /*
1706 * For fast devices, IO may have already completed. If it has, add
1707 * it to the front so we find it first.
1708 */
1709 if (READ_ONCE(req->iopoll_completed))
1710 wq_list_add_head(&req->comp_list, &ctx->iopoll_list);
1711 else
1712 wq_list_add_tail(&req->comp_list, &ctx->iopoll_list);
1713
1714 if (unlikely(needs_lock)) {
1715 /*
1716 * If IORING_SETUP_SQPOLL is enabled, sqes are either handle
1717 * in sq thread task context or in io worker task context. If
1718 * current task context is sq thread, we don't need to check
1719 * whether should wake up sq thread.
1720 */
1721 if ((ctx->flags & IORING_SETUP_SQPOLL) &&
1722 wq_has_sleeper(&ctx->sq_data->wait))
1723 wake_up(&ctx->sq_data->wait);
1724
1725 mutex_unlock(&ctx->uring_lock);
1726 }
1727 }
1728
io_file_get_flags(struct file * file)1729 unsigned int io_file_get_flags(struct file *file)
1730 {
1731 unsigned int res = 0;
1732
1733 if (S_ISREG(file_inode(file)->i_mode))
1734 res |= REQ_F_ISREG;
1735 if ((file->f_flags & O_NONBLOCK) || (file->f_mode & FMODE_NOWAIT))
1736 res |= REQ_F_SUPPORT_NOWAIT;
1737 return res;
1738 }
1739
io_alloc_async_data(struct io_kiocb * req)1740 bool io_alloc_async_data(struct io_kiocb *req)
1741 {
1742 WARN_ON_ONCE(!io_cold_defs[req->opcode].async_size);
1743 req->async_data = kmalloc(io_cold_defs[req->opcode].async_size, GFP_KERNEL);
1744 if (req->async_data) {
1745 req->flags |= REQ_F_ASYNC_DATA;
1746 return false;
1747 }
1748 return true;
1749 }
1750
io_req_prep_async(struct io_kiocb * req)1751 int io_req_prep_async(struct io_kiocb *req)
1752 {
1753 const struct io_cold_def *cdef = &io_cold_defs[req->opcode];
1754 const struct io_issue_def *def = &io_issue_defs[req->opcode];
1755
1756 /* assign early for deferred execution for non-fixed file */
1757 if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file)
1758 req->file = io_file_get_normal(req, req->cqe.fd);
1759 if (!cdef->prep_async)
1760 return 0;
1761 if (WARN_ON_ONCE(req_has_async_data(req)))
1762 return -EFAULT;
1763 if (!def->manual_alloc) {
1764 if (io_alloc_async_data(req))
1765 return -EAGAIN;
1766 }
1767 return cdef->prep_async(req);
1768 }
1769
io_get_sequence(struct io_kiocb * req)1770 static u32 io_get_sequence(struct io_kiocb *req)
1771 {
1772 u32 seq = req->ctx->cached_sq_head;
1773 struct io_kiocb *cur;
1774
1775 /* need original cached_sq_head, but it was increased for each req */
1776 io_for_each_link(cur, req)
1777 seq--;
1778 return seq;
1779 }
1780
io_drain_req(struct io_kiocb * req)1781 static __cold void io_drain_req(struct io_kiocb *req)
1782 __must_hold(&ctx->uring_lock)
1783 {
1784 struct io_ring_ctx *ctx = req->ctx;
1785 struct io_defer_entry *de;
1786 int ret;
1787 u32 seq = io_get_sequence(req);
1788
1789 /* Still need defer if there is pending req in defer list. */
1790 spin_lock(&ctx->completion_lock);
1791 if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list)) {
1792 spin_unlock(&ctx->completion_lock);
1793 queue:
1794 ctx->drain_active = false;
1795 io_req_task_queue(req);
1796 return;
1797 }
1798 spin_unlock(&ctx->completion_lock);
1799
1800 io_prep_async_link(req);
1801 de = kmalloc(sizeof(*de), GFP_KERNEL);
1802 if (!de) {
1803 ret = -ENOMEM;
1804 io_req_defer_failed(req, ret);
1805 return;
1806 }
1807
1808 spin_lock(&ctx->completion_lock);
1809 if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
1810 spin_unlock(&ctx->completion_lock);
1811 kfree(de);
1812 goto queue;
1813 }
1814
1815 trace_io_uring_defer(req);
1816 de->req = req;
1817 de->seq = seq;
1818 list_add_tail(&de->list, &ctx->defer_list);
1819 spin_unlock(&ctx->completion_lock);
1820 }
1821
io_assign_file(struct io_kiocb * req,const struct io_issue_def * def,unsigned int issue_flags)1822 static bool io_assign_file(struct io_kiocb *req, const struct io_issue_def *def,
1823 unsigned int issue_flags)
1824 {
1825 if (req->file || !def->needs_file)
1826 return true;
1827
1828 if (req->flags & REQ_F_FIXED_FILE)
1829 req->file = io_file_get_fixed(req, req->cqe.fd, issue_flags);
1830 else
1831 req->file = io_file_get_normal(req, req->cqe.fd);
1832
1833 return !!req->file;
1834 }
1835
io_issue_sqe(struct io_kiocb * req,unsigned int issue_flags)1836 static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
1837 {
1838 const struct io_issue_def *def = &io_issue_defs[req->opcode];
1839 const struct cred *creds = NULL;
1840 int ret;
1841
1842 if (unlikely(!io_assign_file(req, def, issue_flags)))
1843 return -EBADF;
1844
1845 if (unlikely((req->flags & REQ_F_CREDS) && req->creds != current_cred()))
1846 creds = override_creds(req->creds);
1847
1848 if (!def->audit_skip)
1849 audit_uring_entry(req->opcode);
1850
1851 ret = def->issue(req, issue_flags);
1852
1853 if (!def->audit_skip)
1854 audit_uring_exit(!ret, ret);
1855
1856 if (creds)
1857 revert_creds(creds);
1858
1859 if (ret == IOU_OK) {
1860 if (issue_flags & IO_URING_F_COMPLETE_DEFER)
1861 io_req_complete_defer(req);
1862 else
1863 io_req_complete_post(req, issue_flags);
1864
1865 return 0;
1866 }
1867
1868 if (ret != IOU_ISSUE_SKIP_COMPLETE)
1869 return ret;
1870
1871 /* If the op doesn't have a file, we're not polling for it */
1872 if ((req->ctx->flags & IORING_SETUP_IOPOLL) && def->iopoll_queue)
1873 io_iopoll_req_issued(req, issue_flags);
1874
1875 return 0;
1876 }
1877
io_poll_issue(struct io_kiocb * req,struct io_tw_state * ts)1878 int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts)
1879 {
1880 io_tw_lock(req->ctx, ts);
1881 return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_MULTISHOT|
1882 IO_URING_F_COMPLETE_DEFER);
1883 }
1884
io_wq_free_work(struct io_wq_work * work)1885 struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
1886 {
1887 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
1888 struct io_kiocb *nxt = NULL;
1889
1890 if (req_ref_put_and_test(req)) {
1891 if (req->flags & IO_REQ_LINK_FLAGS)
1892 nxt = io_req_find_next(req);
1893 io_free_req(req);
1894 }
1895 return nxt ? &nxt->work : NULL;
1896 }
1897
io_wq_submit_work(struct io_wq_work * work)1898 void io_wq_submit_work(struct io_wq_work *work)
1899 {
1900 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
1901 const struct io_issue_def *def = &io_issue_defs[req->opcode];
1902 unsigned int issue_flags = IO_URING_F_UNLOCKED | IO_URING_F_IOWQ;
1903 bool needs_poll = false;
1904 int ret = 0, err = -ECANCELED;
1905
1906 /* one will be dropped by ->io_wq_free_work() after returning to io-wq */
1907 if (!(req->flags & REQ_F_REFCOUNT))
1908 __io_req_set_refcount(req, 2);
1909 else
1910 req_ref_get(req);
1911
1912 io_arm_ltimeout(req);
1913
1914 /* either cancelled or io-wq is dying, so don't touch tctx->iowq */
1915 if (work->flags & IO_WQ_WORK_CANCEL) {
1916 fail:
1917 io_req_task_queue_fail(req, err);
1918 return;
1919 }
1920 if (!io_assign_file(req, def, issue_flags)) {
1921 err = -EBADF;
1922 work->flags |= IO_WQ_WORK_CANCEL;
1923 goto fail;
1924 }
1925
1926 if (req->flags & REQ_F_FORCE_ASYNC) {
1927 bool opcode_poll = def->pollin || def->pollout;
1928
1929 if (opcode_poll && file_can_poll(req->file)) {
1930 needs_poll = true;
1931 issue_flags |= IO_URING_F_NONBLOCK;
1932 }
1933 }
1934
1935 do {
1936 ret = io_issue_sqe(req, issue_flags);
1937 if (ret != -EAGAIN)
1938 break;
1939
1940 /*
1941 * If REQ_F_NOWAIT is set, then don't wait or retry with
1942 * poll. -EAGAIN is final for that case.
1943 */
1944 if (req->flags & REQ_F_NOWAIT)
1945 break;
1946
1947 /*
1948 * We can get EAGAIN for iopolled IO even though we're
1949 * forcing a sync submission from here, since we can't
1950 * wait for request slots on the block side.
1951 */
1952 if (!needs_poll) {
1953 if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
1954 break;
1955 if (io_wq_worker_stopped())
1956 break;
1957 cond_resched();
1958 continue;
1959 }
1960
1961 if (io_arm_poll_handler(req, issue_flags) == IO_APOLL_OK)
1962 return;
1963 /* aborted or ready, in either case retry blocking */
1964 needs_poll = false;
1965 issue_flags &= ~IO_URING_F_NONBLOCK;
1966 } while (1);
1967
1968 /* avoid locking problems by failing it from a clean context */
1969 if (ret < 0)
1970 io_req_task_queue_fail(req, ret);
1971 }
1972
io_file_get_fixed(struct io_kiocb * req,int fd,unsigned int issue_flags)1973 inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
1974 unsigned int issue_flags)
1975 {
1976 struct io_ring_ctx *ctx = req->ctx;
1977 struct io_fixed_file *slot;
1978 struct file *file = NULL;
1979
1980 io_ring_submit_lock(ctx, issue_flags);
1981
1982 if (unlikely((unsigned int)fd >= ctx->nr_user_files))
1983 goto out;
1984 fd = array_index_nospec(fd, ctx->nr_user_files);
1985 slot = io_fixed_file_slot(&ctx->file_table, fd);
1986 file = io_slot_file(slot);
1987 req->flags |= io_slot_flags(slot);
1988 io_req_set_rsrc_node(req, ctx, 0);
1989 out:
1990 io_ring_submit_unlock(ctx, issue_flags);
1991 return file;
1992 }
1993
io_file_get_normal(struct io_kiocb * req,int fd)1994 struct file *io_file_get_normal(struct io_kiocb *req, int fd)
1995 {
1996 struct file *file = fget(fd);
1997
1998 trace_io_uring_file_get(req, fd);
1999
2000 /* we don't allow fixed io_uring files */
2001 if (file && io_is_uring_fops(file))
2002 io_req_track_inflight(req);
2003 return file;
2004 }
2005
io_queue_async(struct io_kiocb * req,int ret)2006 static void io_queue_async(struct io_kiocb *req, int ret)
2007 __must_hold(&req->ctx->uring_lock)
2008 {
2009 struct io_kiocb *linked_timeout;
2010
2011 if (ret != -EAGAIN || (req->flags & REQ_F_NOWAIT)) {
2012 io_req_defer_failed(req, ret);
2013 return;
2014 }
2015
2016 linked_timeout = io_prep_linked_timeout(req);
2017
2018 switch (io_arm_poll_handler(req, 0)) {
2019 case IO_APOLL_READY:
2020 io_kbuf_recycle(req, 0);
2021 io_req_task_queue(req);
2022 break;
2023 case IO_APOLL_ABORTED:
2024 io_kbuf_recycle(req, 0);
2025 io_queue_iowq(req, NULL);
2026 break;
2027 case IO_APOLL_OK:
2028 break;
2029 }
2030
2031 if (linked_timeout)
2032 io_queue_linked_timeout(linked_timeout);
2033 }
2034
io_queue_sqe(struct io_kiocb * req)2035 static inline void io_queue_sqe(struct io_kiocb *req)
2036 __must_hold(&req->ctx->uring_lock)
2037 {
2038 int ret;
2039
2040 ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
2041
2042 /*
2043 * We async punt it if the file wasn't marked NOWAIT, or if the file
2044 * doesn't support non-blocking read/write attempts
2045 */
2046 if (likely(!ret))
2047 io_arm_ltimeout(req);
2048 else
2049 io_queue_async(req, ret);
2050 }
2051
io_queue_sqe_fallback(struct io_kiocb * req)2052 static void io_queue_sqe_fallback(struct io_kiocb *req)
2053 __must_hold(&req->ctx->uring_lock)
2054 {
2055 if (unlikely(req->flags & REQ_F_FAIL)) {
2056 /*
2057 * We don't submit, fail them all, for that replace hardlinks
2058 * with normal links. Extra REQ_F_LINK is tolerated.
2059 */
2060 req->flags &= ~REQ_F_HARDLINK;
2061 req->flags |= REQ_F_LINK;
2062 io_req_defer_failed(req, req->cqe.res);
2063 } else {
2064 int ret = io_req_prep_async(req);
2065
2066 if (unlikely(ret)) {
2067 io_req_defer_failed(req, ret);
2068 return;
2069 }
2070
2071 if (unlikely(req->ctx->drain_active))
2072 io_drain_req(req);
2073 else
2074 io_queue_iowq(req, NULL);
2075 }
2076 }
2077
2078 /*
2079 * Check SQE restrictions (opcode and flags).
2080 *
2081 * Returns 'true' if SQE is allowed, 'false' otherwise.
2082 */
io_check_restriction(struct io_ring_ctx * ctx,struct io_kiocb * req,unsigned int sqe_flags)2083 static inline bool io_check_restriction(struct io_ring_ctx *ctx,
2084 struct io_kiocb *req,
2085 unsigned int sqe_flags)
2086 {
2087 if (!test_bit(req->opcode, ctx->restrictions.sqe_op))
2088 return false;
2089
2090 if ((sqe_flags & ctx->restrictions.sqe_flags_required) !=
2091 ctx->restrictions.sqe_flags_required)
2092 return false;
2093
2094 if (sqe_flags & ~(ctx->restrictions.sqe_flags_allowed |
2095 ctx->restrictions.sqe_flags_required))
2096 return false;
2097
2098 return true;
2099 }
2100
io_init_req_drain(struct io_kiocb * req)2101 static void io_init_req_drain(struct io_kiocb *req)
2102 {
2103 struct io_ring_ctx *ctx = req->ctx;
2104 struct io_kiocb *head = ctx->submit_state.link.head;
2105
2106 ctx->drain_active = true;
2107 if (head) {
2108 /*
2109 * If we need to drain a request in the middle of a link, drain
2110 * the head request and the next request/link after the current
2111 * link. Considering sequential execution of links,
2112 * REQ_F_IO_DRAIN will be maintained for every request of our
2113 * link.
2114 */
2115 head->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
2116 ctx->drain_next = true;
2117 }
2118 }
2119
io_init_fail_req(struct io_kiocb * req,int err)2120 static __cold int io_init_fail_req(struct io_kiocb *req, int err)
2121 {
2122 /* ensure per-opcode data is cleared if we fail before prep */
2123 memset(&req->cmd.data, 0, sizeof(req->cmd.data));
2124 return err;
2125 }
2126
io_init_req(struct io_ring_ctx * ctx,struct io_kiocb * req,const struct io_uring_sqe * sqe)2127 static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
2128 const struct io_uring_sqe *sqe)
2129 __must_hold(&ctx->uring_lock)
2130 {
2131 const struct io_issue_def *def;
2132 unsigned int sqe_flags;
2133 int personality;
2134 u8 opcode;
2135
2136 /* req is partially pre-initialised, see io_preinit_req() */
2137 req->opcode = opcode = READ_ONCE(sqe->opcode);
2138 /* same numerical values with corresponding REQ_F_*, safe to copy */
2139 req->flags = sqe_flags = READ_ONCE(sqe->flags);
2140 req->cqe.user_data = READ_ONCE(sqe->user_data);
2141 req->file = NULL;
2142 req->rsrc_node = NULL;
2143 req->task = current;
2144
2145 if (unlikely(opcode >= IORING_OP_LAST)) {
2146 req->opcode = 0;
2147 return io_init_fail_req(req, -EINVAL);
2148 }
2149 def = &io_issue_defs[opcode];
2150 if (unlikely(sqe_flags & ~SQE_COMMON_FLAGS)) {
2151 /* enforce forwards compatibility on users */
2152 if (sqe_flags & ~SQE_VALID_FLAGS)
2153 return io_init_fail_req(req, -EINVAL);
2154 if (sqe_flags & IOSQE_BUFFER_SELECT) {
2155 if (!def->buffer_select)
2156 return io_init_fail_req(req, -EOPNOTSUPP);
2157 req->buf_index = READ_ONCE(sqe->buf_group);
2158 }
2159 if (sqe_flags & IOSQE_CQE_SKIP_SUCCESS)
2160 ctx->drain_disabled = true;
2161 if (sqe_flags & IOSQE_IO_DRAIN) {
2162 if (ctx->drain_disabled)
2163 return io_init_fail_req(req, -EOPNOTSUPP);
2164 io_init_req_drain(req);
2165 }
2166 }
2167 if (unlikely(ctx->restricted || ctx->drain_active || ctx->drain_next)) {
2168 if (ctx->restricted && !io_check_restriction(ctx, req, sqe_flags))
2169 return io_init_fail_req(req, -EACCES);
2170 /* knock it to the slow queue path, will be drained there */
2171 if (ctx->drain_active)
2172 req->flags |= REQ_F_FORCE_ASYNC;
2173 /* if there is no link, we're at "next" request and need to drain */
2174 if (unlikely(ctx->drain_next) && !ctx->submit_state.link.head) {
2175 ctx->drain_next = false;
2176 ctx->drain_active = true;
2177 req->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
2178 }
2179 }
2180
2181 if (!def->ioprio && sqe->ioprio)
2182 return io_init_fail_req(req, -EINVAL);
2183 if (!def->iopoll && (ctx->flags & IORING_SETUP_IOPOLL))
2184 return io_init_fail_req(req, -EINVAL);
2185
2186 if (def->needs_file) {
2187 struct io_submit_state *state = &ctx->submit_state;
2188
2189 req->cqe.fd = READ_ONCE(sqe->fd);
2190
2191 /*
2192 * Plug now if we have more than 2 IO left after this, and the
2193 * target is potentially a read/write to block based storage.
2194 */
2195 if (state->need_plug && def->plug) {
2196 state->plug_started = true;
2197 state->need_plug = false;
2198 blk_start_plug_nr_ios(&state->plug, state->submit_nr);
2199 }
2200 }
2201
2202 personality = READ_ONCE(sqe->personality);
2203 if (personality) {
2204 int ret;
2205
2206 req->creds = xa_load(&ctx->personalities, personality);
2207 if (!req->creds)
2208 return io_init_fail_req(req, -EINVAL);
2209 get_cred(req->creds);
2210 ret = security_uring_override_creds(req->creds);
2211 if (ret) {
2212 put_cred(req->creds);
2213 return io_init_fail_req(req, ret);
2214 }
2215 req->flags |= REQ_F_CREDS;
2216 }
2217
2218 return def->prep(req, sqe);
2219 }
2220
io_submit_fail_init(const struct io_uring_sqe * sqe,struct io_kiocb * req,int ret)2221 static __cold int io_submit_fail_init(const struct io_uring_sqe *sqe,
2222 struct io_kiocb *req, int ret)
2223 {
2224 struct io_ring_ctx *ctx = req->ctx;
2225 struct io_submit_link *link = &ctx->submit_state.link;
2226 struct io_kiocb *head = link->head;
2227
2228 trace_io_uring_req_failed(sqe, req, ret);
2229
2230 /*
2231 * Avoid breaking links in the middle as it renders links with SQPOLL
2232 * unusable. Instead of failing eagerly, continue assembling the link if
2233 * applicable and mark the head with REQ_F_FAIL. The link flushing code
2234 * should find the flag and handle the rest.
2235 */
2236 req_fail_link_node(req, ret);
2237 if (head && !(head->flags & REQ_F_FAIL))
2238 req_fail_link_node(head, -ECANCELED);
2239
2240 if (!(req->flags & IO_REQ_LINK_FLAGS)) {
2241 if (head) {
2242 link->last->link = req;
2243 link->head = NULL;
2244 req = head;
2245 }
2246 io_queue_sqe_fallback(req);
2247 return ret;
2248 }
2249
2250 if (head)
2251 link->last->link = req;
2252 else
2253 link->head = req;
2254 link->last = req;
2255 return 0;
2256 }
2257
io_submit_sqe(struct io_ring_ctx * ctx,struct io_kiocb * req,const struct io_uring_sqe * sqe)2258 static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
2259 const struct io_uring_sqe *sqe)
2260 __must_hold(&ctx->uring_lock)
2261 {
2262 struct io_submit_link *link = &ctx->submit_state.link;
2263 int ret;
2264
2265 ret = io_init_req(ctx, req, sqe);
2266 if (unlikely(ret))
2267 return io_submit_fail_init(sqe, req, ret);
2268
2269 trace_io_uring_submit_req(req);
2270
2271 /*
2272 * If we already have a head request, queue this one for async
2273 * submittal once the head completes. If we don't have a head but
2274 * IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
2275 * submitted sync once the chain is complete. If none of those
2276 * conditions are true (normal request), then just queue it.
2277 */
2278 if (unlikely(link->head)) {
2279 ret = io_req_prep_async(req);
2280 if (unlikely(ret))
2281 return io_submit_fail_init(sqe, req, ret);
2282
2283 trace_io_uring_link(req, link->head);
2284 link->last->link = req;
2285 link->last = req;
2286
2287 if (req->flags & IO_REQ_LINK_FLAGS)
2288 return 0;
2289 /* last request of the link, flush it */
2290 req = link->head;
2291 link->head = NULL;
2292 if (req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL))
2293 goto fallback;
2294
2295 } else if (unlikely(req->flags & (IO_REQ_LINK_FLAGS |
2296 REQ_F_FORCE_ASYNC | REQ_F_FAIL))) {
2297 if (req->flags & IO_REQ_LINK_FLAGS) {
2298 link->head = req;
2299 link->last = req;
2300 } else {
2301 fallback:
2302 io_queue_sqe_fallback(req);
2303 }
2304 return 0;
2305 }
2306
2307 io_queue_sqe(req);
2308 return 0;
2309 }
2310
2311 /*
2312 * Batched submission is done, ensure local IO is flushed out.
2313 */
io_submit_state_end(struct io_ring_ctx * ctx)2314 static void io_submit_state_end(struct io_ring_ctx *ctx)
2315 {
2316 struct io_submit_state *state = &ctx->submit_state;
2317
2318 if (unlikely(state->link.head))
2319 io_queue_sqe_fallback(state->link.head);
2320 /* flush only after queuing links as they can generate completions */
2321 io_submit_flush_completions(ctx);
2322 if (state->plug_started)
2323 blk_finish_plug(&state->plug);
2324 }
2325
2326 /*
2327 * Start submission side cache.
2328 */
io_submit_state_start(struct io_submit_state * state,unsigned int max_ios)2329 static void io_submit_state_start(struct io_submit_state *state,
2330 unsigned int max_ios)
2331 {
2332 state->plug_started = false;
2333 state->need_plug = max_ios > 2;
2334 state->submit_nr = max_ios;
2335 /* set only head, no need to init link_last in advance */
2336 state->link.head = NULL;
2337 }
2338
io_commit_sqring(struct io_ring_ctx * ctx)2339 static void io_commit_sqring(struct io_ring_ctx *ctx)
2340 {
2341 struct io_rings *rings = ctx->rings;
2342
2343 /*
2344 * Ensure any loads from the SQEs are done at this point,
2345 * since once we write the new head, the application could
2346 * write new data to them.
2347 */
2348 smp_store_release(&rings->sq.head, ctx->cached_sq_head);
2349 }
2350
2351 /*
2352 * Fetch an sqe, if one is available. Note this returns a pointer to memory
2353 * that is mapped by userspace. This means that care needs to be taken to
2354 * ensure that reads are stable, as we cannot rely on userspace always
2355 * being a good citizen. If members of the sqe are validated and then later
2356 * used, it's important that those reads are done through READ_ONCE() to
2357 * prevent a re-load down the line.
2358 */
io_get_sqe(struct io_ring_ctx * ctx,const struct io_uring_sqe ** sqe)2359 static bool io_get_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe)
2360 {
2361 unsigned mask = ctx->sq_entries - 1;
2362 unsigned head = ctx->cached_sq_head++ & mask;
2363
2364 if (!(ctx->flags & IORING_SETUP_NO_SQARRAY)) {
2365 head = READ_ONCE(ctx->sq_array[head]);
2366 if (unlikely(head >= ctx->sq_entries)) {
2367 /* drop invalid entries */
2368 spin_lock(&ctx->completion_lock);
2369 ctx->cq_extra--;
2370 spin_unlock(&ctx->completion_lock);
2371 WRITE_ONCE(ctx->rings->sq_dropped,
2372 READ_ONCE(ctx->rings->sq_dropped) + 1);
2373 return false;
2374 }
2375 }
2376
2377 /*
2378 * The cached sq head (or cq tail) serves two purposes:
2379 *
2380 * 1) allows us to batch the cost of updating the user visible
2381 * head updates.
2382 * 2) allows the kernel side to track the head on its own, even
2383 * though the application is the one updating it.
2384 */
2385
2386 /* double index for 128-byte SQEs, twice as long */
2387 if (ctx->flags & IORING_SETUP_SQE128)
2388 head <<= 1;
2389 *sqe = &ctx->sq_sqes[head];
2390 return true;
2391 }
2392
io_submit_sqes(struct io_ring_ctx * ctx,unsigned int nr)2393 int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
2394 __must_hold(&ctx->uring_lock)
2395 {
2396 unsigned int entries = io_sqring_entries(ctx);
2397 unsigned int left;
2398 int ret;
2399
2400 if (unlikely(!entries))
2401 return 0;
2402 /* make sure SQ entry isn't read before tail */
2403 ret = left = min(nr, entries);
2404 io_get_task_refs(left);
2405 io_submit_state_start(&ctx->submit_state, left);
2406
2407 do {
2408 const struct io_uring_sqe *sqe;
2409 struct io_kiocb *req;
2410
2411 if (unlikely(!io_alloc_req(ctx, &req)))
2412 break;
2413 if (unlikely(!io_get_sqe(ctx, &sqe))) {
2414 io_req_add_to_cache(req, ctx);
2415 break;
2416 }
2417
2418 /*
2419 * Continue submitting even for sqe failure if the
2420 * ring was setup with IORING_SETUP_SUBMIT_ALL
2421 */
2422 if (unlikely(io_submit_sqe(ctx, req, sqe)) &&
2423 !(ctx->flags & IORING_SETUP_SUBMIT_ALL)) {
2424 left--;
2425 break;
2426 }
2427 } while (--left);
2428
2429 if (unlikely(left)) {
2430 ret -= left;
2431 /* try again if it submitted nothing and can't allocate a req */
2432 if (!ret && io_req_cache_empty(ctx))
2433 ret = -EAGAIN;
2434 current->io_uring->cached_refs += left;
2435 }
2436
2437 io_submit_state_end(ctx);
2438 /* Commit SQ ring head once we've consumed and submitted all SQEs */
2439 io_commit_sqring(ctx);
2440 return ret;
2441 }
2442
2443 struct io_wait_queue {
2444 struct wait_queue_entry wq;
2445 struct io_ring_ctx *ctx;
2446 unsigned cq_tail;
2447 unsigned nr_timeouts;
2448 ktime_t timeout;
2449 };
2450
io_has_work(struct io_ring_ctx * ctx)2451 static inline bool io_has_work(struct io_ring_ctx *ctx)
2452 {
2453 return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
2454 !llist_empty(&ctx->work_llist);
2455 }
2456
io_should_wake(struct io_wait_queue * iowq)2457 static inline bool io_should_wake(struct io_wait_queue *iowq)
2458 {
2459 struct io_ring_ctx *ctx = iowq->ctx;
2460 int dist = READ_ONCE(ctx->rings->cq.tail) - (int) iowq->cq_tail;
2461
2462 /*
2463 * Wake up if we have enough events, or if a timeout occurred since we
2464 * started waiting. For timeouts, we always want to return to userspace,
2465 * regardless of event count.
2466 */
2467 return dist >= 0 || atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
2468 }
2469
io_wake_function(struct wait_queue_entry * curr,unsigned int mode,int wake_flags,void * key)2470 static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
2471 int wake_flags, void *key)
2472 {
2473 struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue, wq);
2474
2475 /*
2476 * Cannot safely flush overflowed CQEs from here, ensure we wake up
2477 * the task, and the next invocation will do it.
2478 */
2479 if (io_should_wake(iowq) || io_has_work(iowq->ctx))
2480 return autoremove_wake_function(curr, mode, wake_flags, key);
2481 return -1;
2482 }
2483
io_run_task_work_sig(struct io_ring_ctx * ctx)2484 int io_run_task_work_sig(struct io_ring_ctx *ctx)
2485 {
2486 if (!llist_empty(&ctx->work_llist)) {
2487 __set_current_state(TASK_RUNNING);
2488 if (io_run_local_work(ctx, INT_MAX) > 0)
2489 return 0;
2490 }
2491 if (io_run_task_work() > 0)
2492 return 0;
2493 if (task_sigpending(current))
2494 return -EINTR;
2495 return 0;
2496 }
2497
current_pending_io(void)2498 static bool current_pending_io(void)
2499 {
2500 struct io_uring_task *tctx = current->io_uring;
2501
2502 if (!tctx)
2503 return false;
2504 return percpu_counter_read_positive(&tctx->inflight);
2505 }
2506
2507 /* when returns >0, the caller should retry */
io_cqring_wait_schedule(struct io_ring_ctx * ctx,struct io_wait_queue * iowq)2508 static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
2509 struct io_wait_queue *iowq)
2510 {
2511 int ret;
2512
2513 if (unlikely(READ_ONCE(ctx->check_cq)))
2514 return 1;
2515 if (unlikely(!llist_empty(&ctx->work_llist)))
2516 return 1;
2517 if (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL)))
2518 return 1;
2519 if (unlikely(task_sigpending(current)))
2520 return -EINTR;
2521 if (unlikely(io_should_wake(iowq)))
2522 return 0;
2523
2524 /*
2525 * Mark us as being in io_wait if we have pending requests, so cpufreq
2526 * can take into account that the task is waiting for IO - turns out
2527 * to be important for low QD IO.
2528 */
2529 if (current_pending_io())
2530 current->in_iowait = 1;
2531 ret = 0;
2532 if (iowq->timeout == KTIME_MAX)
2533 schedule();
2534 else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS))
2535 ret = -ETIME;
2536 current->in_iowait = 0;
2537 return ret;
2538 }
2539
2540 /*
2541 * Wait until events become available, if we don't already have some. The
2542 * application must reap them itself, as they reside on the shared cq ring.
2543 */
io_cqring_wait(struct io_ring_ctx * ctx,int min_events,const sigset_t __user * sig,size_t sigsz,struct __kernel_timespec __user * uts)2544 static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
2545 const sigset_t __user *sig, size_t sigsz,
2546 struct __kernel_timespec __user *uts)
2547 {
2548 struct io_wait_queue iowq;
2549 struct io_rings *rings = ctx->rings;
2550 int ret;
2551
2552 if (!io_allowed_run_tw(ctx))
2553 return -EEXIST;
2554 if (!llist_empty(&ctx->work_llist))
2555 io_run_local_work(ctx, min_events);
2556 io_run_task_work();
2557 io_cqring_overflow_flush(ctx);
2558 /* if user messes with these they will just get an early return */
2559 if (__io_cqring_events_user(ctx) >= min_events)
2560 return 0;
2561
2562 init_waitqueue_func_entry(&iowq.wq, io_wake_function);
2563 iowq.wq.private = current;
2564 INIT_LIST_HEAD(&iowq.wq.entry);
2565 iowq.ctx = ctx;
2566 iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
2567 iowq.cq_tail = READ_ONCE(ctx->rings->cq.head) + min_events;
2568 iowq.timeout = KTIME_MAX;
2569
2570 if (uts) {
2571 struct timespec64 ts;
2572
2573 if (get_timespec64(&ts, uts))
2574 return -EFAULT;
2575 iowq.timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
2576 }
2577
2578 if (sig) {
2579 #ifdef CONFIG_COMPAT
2580 if (in_compat_syscall())
2581 ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
2582 sigsz);
2583 else
2584 #endif
2585 ret = set_user_sigmask(sig, sigsz);
2586
2587 if (ret)
2588 return ret;
2589 }
2590
2591 trace_io_uring_cqring_wait(ctx, min_events);
2592 do {
2593 int nr_wait = (int) iowq.cq_tail - READ_ONCE(ctx->rings->cq.tail);
2594 unsigned long check_cq;
2595
2596 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
2597 atomic_set(&ctx->cq_wait_nr, nr_wait);
2598 set_current_state(TASK_INTERRUPTIBLE);
2599 } else {
2600 prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
2601 TASK_INTERRUPTIBLE);
2602 }
2603
2604 ret = io_cqring_wait_schedule(ctx, &iowq);
2605 __set_current_state(TASK_RUNNING);
2606 atomic_set(&ctx->cq_wait_nr, 0);
2607
2608 /*
2609 * Run task_work after scheduling and before io_should_wake().
2610 * If we got woken because of task_work being processed, run it
2611 * now rather than let the caller do another wait loop.
2612 */
2613 io_run_task_work();
2614 if (!llist_empty(&ctx->work_llist))
2615 io_run_local_work(ctx, nr_wait);
2616
2617 /*
2618 * Non-local task_work will be run on exit to userspace, but
2619 * if we're using DEFER_TASKRUN, then we could have waited
2620 * with a timeout for a number of requests. If the timeout
2621 * hits, we could have some requests ready to process. Ensure
2622 * this break is _after_ we have run task_work, to avoid
2623 * deferring running potentially pending requests until the
2624 * next time we wait for events.
2625 */
2626 if (ret < 0)
2627 break;
2628
2629 check_cq = READ_ONCE(ctx->check_cq);
2630 if (unlikely(check_cq)) {
2631 /* let the caller flush overflows, retry */
2632 if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
2633 io_cqring_do_overflow_flush(ctx);
2634 if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) {
2635 ret = -EBADR;
2636 break;
2637 }
2638 }
2639
2640 if (io_should_wake(&iowq)) {
2641 ret = 0;
2642 break;
2643 }
2644 cond_resched();
2645 } while (1);
2646
2647 if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
2648 finish_wait(&ctx->cq_wait, &iowq.wq);
2649 restore_saved_sigmask_unless(ret == -EINTR);
2650
2651 return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
2652 }
2653
io_mem_free(void * ptr)2654 void io_mem_free(void *ptr)
2655 {
2656 if (!ptr)
2657 return;
2658
2659 folio_put(virt_to_folio(ptr));
2660 }
2661
io_pages_free(struct page *** pages,int npages)2662 static void io_pages_free(struct page ***pages, int npages)
2663 {
2664 struct page **page_array;
2665 int i;
2666
2667 if (!pages)
2668 return;
2669
2670 page_array = *pages;
2671 if (!page_array)
2672 return;
2673
2674 for (i = 0; i < npages; i++)
2675 unpin_user_page(page_array[i]);
2676 kvfree(page_array);
2677 *pages = NULL;
2678 }
2679
__io_uaddr_map(struct page *** pages,unsigned short * npages,unsigned long uaddr,size_t size)2680 static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
2681 unsigned long uaddr, size_t size)
2682 {
2683 struct page **page_array;
2684 unsigned int nr_pages;
2685 void *page_addr;
2686 int ret, i, pinned;
2687
2688 *npages = 0;
2689
2690 if (uaddr & (PAGE_SIZE - 1) || !size)
2691 return ERR_PTR(-EINVAL);
2692
2693 nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2694 if (nr_pages > USHRT_MAX)
2695 return ERR_PTR(-EINVAL);
2696 page_array = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
2697 if (!page_array)
2698 return ERR_PTR(-ENOMEM);
2699
2700
2701 pinned = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
2702 page_array);
2703 if (pinned != nr_pages) {
2704 ret = (pinned < 0) ? pinned : -EFAULT;
2705 goto free_pages;
2706 }
2707
2708 page_addr = page_address(page_array[0]);
2709 for (i = 0; i < nr_pages; i++) {
2710 ret = -EINVAL;
2711
2712 /*
2713 * Can't support mapping user allocated ring memory on 32-bit
2714 * archs where it could potentially reside in highmem. Just
2715 * fail those with -EINVAL, just like we did on kernels that
2716 * didn't support this feature.
2717 */
2718 if (PageHighMem(page_array[i]))
2719 goto free_pages;
2720
2721 /*
2722 * No support for discontig pages for now, should either be a
2723 * single normal page, or a huge page. Later on we can add
2724 * support for remapping discontig pages, for now we will
2725 * just fail them with EINVAL.
2726 */
2727 if (page_address(page_array[i]) != page_addr)
2728 goto free_pages;
2729 page_addr += PAGE_SIZE;
2730 }
2731
2732 *pages = page_array;
2733 *npages = nr_pages;
2734 return page_to_virt(page_array[0]);
2735
2736 free_pages:
2737 io_pages_free(&page_array, pinned > 0 ? pinned : 0);
2738 return ERR_PTR(ret);
2739 }
2740
io_rings_map(struct io_ring_ctx * ctx,unsigned long uaddr,size_t size)2741 static void *io_rings_map(struct io_ring_ctx *ctx, unsigned long uaddr,
2742 size_t size)
2743 {
2744 return __io_uaddr_map(&ctx->ring_pages, &ctx->n_ring_pages, uaddr,
2745 size);
2746 }
2747
io_sqes_map(struct io_ring_ctx * ctx,unsigned long uaddr,size_t size)2748 static void *io_sqes_map(struct io_ring_ctx *ctx, unsigned long uaddr,
2749 size_t size)
2750 {
2751 return __io_uaddr_map(&ctx->sqe_pages, &ctx->n_sqe_pages, uaddr,
2752 size);
2753 }
2754
io_rings_free(struct io_ring_ctx * ctx)2755 static void io_rings_free(struct io_ring_ctx *ctx)
2756 {
2757 if (!(ctx->flags & IORING_SETUP_NO_MMAP)) {
2758 io_mem_free(ctx->rings);
2759 io_mem_free(ctx->sq_sqes);
2760 } else {
2761 io_pages_free(&ctx->ring_pages, ctx->n_ring_pages);
2762 ctx->n_ring_pages = 0;
2763 io_pages_free(&ctx->sqe_pages, ctx->n_sqe_pages);
2764 ctx->n_sqe_pages = 0;
2765 }
2766
2767 ctx->rings = NULL;
2768 ctx->sq_sqes = NULL;
2769 }
2770
io_mem_alloc(size_t size)2771 void *io_mem_alloc(size_t size)
2772 {
2773 gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
2774 void *ret;
2775
2776 ret = (void *) __get_free_pages(gfp, get_order(size));
2777 if (ret)
2778 return ret;
2779 return ERR_PTR(-ENOMEM);
2780 }
2781
rings_size(struct io_ring_ctx * ctx,unsigned int sq_entries,unsigned int cq_entries,size_t * sq_offset)2782 static unsigned long rings_size(struct io_ring_ctx *ctx, unsigned int sq_entries,
2783 unsigned int cq_entries, size_t *sq_offset)
2784 {
2785 struct io_rings *rings;
2786 size_t off, sq_array_size;
2787
2788 off = struct_size(rings, cqes, cq_entries);
2789 if (off == SIZE_MAX)
2790 return SIZE_MAX;
2791 if (ctx->flags & IORING_SETUP_CQE32) {
2792 if (check_shl_overflow(off, 1, &off))
2793 return SIZE_MAX;
2794 }
2795
2796 #ifdef CONFIG_SMP
2797 off = ALIGN(off, SMP_CACHE_BYTES);
2798 if (off == 0)
2799 return SIZE_MAX;
2800 #endif
2801
2802 if (ctx->flags & IORING_SETUP_NO_SQARRAY) {
2803 if (sq_offset)
2804 *sq_offset = SIZE_MAX;
2805 return off;
2806 }
2807
2808 if (sq_offset)
2809 *sq_offset = off;
2810
2811 sq_array_size = array_size(sizeof(u32), sq_entries);
2812 if (sq_array_size == SIZE_MAX)
2813 return SIZE_MAX;
2814
2815 if (check_add_overflow(off, sq_array_size, &off))
2816 return SIZE_MAX;
2817
2818 return off;
2819 }
2820
io_eventfd_register(struct io_ring_ctx * ctx,void __user * arg,unsigned int eventfd_async)2821 static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
2822 unsigned int eventfd_async)
2823 {
2824 struct io_ev_fd *ev_fd;
2825 __s32 __user *fds = arg;
2826 int fd;
2827
2828 ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
2829 lockdep_is_held(&ctx->uring_lock));
2830 if (ev_fd)
2831 return -EBUSY;
2832
2833 if (copy_from_user(&fd, fds, sizeof(*fds)))
2834 return -EFAULT;
2835
2836 ev_fd = kmalloc(sizeof(*ev_fd), GFP_KERNEL);
2837 if (!ev_fd)
2838 return -ENOMEM;
2839
2840 ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd);
2841 if (IS_ERR(ev_fd->cq_ev_fd)) {
2842 int ret = PTR_ERR(ev_fd->cq_ev_fd);
2843 kfree(ev_fd);
2844 return ret;
2845 }
2846
2847 spin_lock(&ctx->completion_lock);
2848 ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
2849 spin_unlock(&ctx->completion_lock);
2850
2851 ev_fd->eventfd_async = eventfd_async;
2852 ctx->has_evfd = true;
2853 rcu_assign_pointer(ctx->io_ev_fd, ev_fd);
2854 atomic_set(&ev_fd->refs, 1);
2855 atomic_set(&ev_fd->ops, 0);
2856 return 0;
2857 }
2858
io_eventfd_unregister(struct io_ring_ctx * ctx)2859 static int io_eventfd_unregister(struct io_ring_ctx *ctx)
2860 {
2861 struct io_ev_fd *ev_fd;
2862
2863 ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
2864 lockdep_is_held(&ctx->uring_lock));
2865 if (ev_fd) {
2866 ctx->has_evfd = false;
2867 rcu_assign_pointer(ctx->io_ev_fd, NULL);
2868 if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_FREE_BIT), &ev_fd->ops))
2869 call_rcu(&ev_fd->rcu, io_eventfd_ops);
2870 return 0;
2871 }
2872
2873 return -ENXIO;
2874 }
2875
io_req_caches_free(struct io_ring_ctx * ctx)2876 static void io_req_caches_free(struct io_ring_ctx *ctx)
2877 {
2878 struct io_kiocb *req;
2879 int nr = 0;
2880
2881 mutex_lock(&ctx->uring_lock);
2882 io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
2883
2884 while (!io_req_cache_empty(ctx)) {
2885 req = io_extract_req(ctx);
2886 kmem_cache_free(req_cachep, req);
2887 nr++;
2888 }
2889 if (nr)
2890 percpu_ref_put_many(&ctx->refs, nr);
2891 mutex_unlock(&ctx->uring_lock);
2892 }
2893
io_rsrc_node_cache_free(struct io_cache_entry * entry)2894 static void io_rsrc_node_cache_free(struct io_cache_entry *entry)
2895 {
2896 kfree(container_of(entry, struct io_rsrc_node, cache));
2897 }
2898
io_ring_ctx_free(struct io_ring_ctx * ctx)2899 static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
2900 {
2901 io_sq_thread_finish(ctx);
2902 /* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
2903 if (WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list)))
2904 return;
2905
2906 mutex_lock(&ctx->uring_lock);
2907 if (ctx->buf_data)
2908 __io_sqe_buffers_unregister(ctx);
2909 if (ctx->file_data)
2910 __io_sqe_files_unregister(ctx);
2911 io_cqring_overflow_kill(ctx);
2912 io_eventfd_unregister(ctx);
2913 io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
2914 io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
2915 io_destroy_buffers(ctx);
2916 mutex_unlock(&ctx->uring_lock);
2917 if (ctx->sq_creds)
2918 put_cred(ctx->sq_creds);
2919 if (ctx->submitter_task)
2920 put_task_struct(ctx->submitter_task);
2921
2922 /* there are no registered resources left, nobody uses it */
2923 if (ctx->rsrc_node)
2924 io_rsrc_node_destroy(ctx, ctx->rsrc_node);
2925
2926 WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
2927 WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
2928
2929 io_alloc_cache_free(&ctx->rsrc_node_cache, io_rsrc_node_cache_free);
2930 if (ctx->mm_account) {
2931 mmdrop(ctx->mm_account);
2932 ctx->mm_account = NULL;
2933 }
2934 io_rings_free(ctx);
2935 io_kbuf_mmap_list_free(ctx);
2936
2937 percpu_ref_exit(&ctx->refs);
2938 free_uid(ctx->user);
2939 io_req_caches_free(ctx);
2940 if (ctx->hash_map)
2941 io_wq_put_hash(ctx->hash_map);
2942 kfree(ctx->cancel_table.hbs);
2943 kfree(ctx->cancel_table_locked.hbs);
2944 xa_destroy(&ctx->io_bl_xa);
2945 kfree(ctx);
2946 }
2947
io_activate_pollwq_cb(struct callback_head * cb)2948 static __cold void io_activate_pollwq_cb(struct callback_head *cb)
2949 {
2950 struct io_ring_ctx *ctx = container_of(cb, struct io_ring_ctx,
2951 poll_wq_task_work);
2952
2953 mutex_lock(&ctx->uring_lock);
2954 ctx->poll_activated = true;
2955 mutex_unlock(&ctx->uring_lock);
2956
2957 /*
2958 * Wake ups for some events between start of polling and activation
2959 * might've been lost due to loose synchronisation.
2960 */
2961 wake_up_all(&ctx->poll_wq);
2962 percpu_ref_put(&ctx->refs);
2963 }
2964
io_activate_pollwq(struct io_ring_ctx * ctx)2965 static __cold void io_activate_pollwq(struct io_ring_ctx *ctx)
2966 {
2967 spin_lock(&ctx->completion_lock);
2968 /* already activated or in progress */
2969 if (ctx->poll_activated || ctx->poll_wq_task_work.func)
2970 goto out;
2971 if (WARN_ON_ONCE(!ctx->task_complete))
2972 goto out;
2973 if (!ctx->submitter_task)
2974 goto out;
2975 /*
2976 * with ->submitter_task only the submitter task completes requests, we
2977 * only need to sync with it, which is done by injecting a tw
2978 */
2979 init_task_work(&ctx->poll_wq_task_work, io_activate_pollwq_cb);
2980 percpu_ref_get(&ctx->refs);
2981 if (task_work_add(ctx->submitter_task, &ctx->poll_wq_task_work, TWA_SIGNAL))
2982 percpu_ref_put(&ctx->refs);
2983 out:
2984 spin_unlock(&ctx->completion_lock);
2985 }
2986
io_uring_poll(struct file * file,poll_table * wait)2987 static __poll_t io_uring_poll(struct file *file, poll_table *wait)
2988 {
2989 struct io_ring_ctx *ctx = file->private_data;
2990 __poll_t mask = 0;
2991
2992 if (unlikely(!ctx->poll_activated))
2993 io_activate_pollwq(ctx);
2994
2995 poll_wait(file, &ctx->poll_wq, wait);
2996 /*
2997 * synchronizes with barrier from wq_has_sleeper call in
2998 * io_commit_cqring
2999 */
3000 smp_rmb();
3001 if (!io_sqring_full(ctx))
3002 mask |= EPOLLOUT | EPOLLWRNORM;
3003
3004 /*
3005 * Don't flush cqring overflow list here, just do a simple check.
3006 * Otherwise there could possible be ABBA deadlock:
3007 * CPU0 CPU1
3008 * ---- ----
3009 * lock(&ctx->uring_lock);
3010 * lock(&ep->mtx);
3011 * lock(&ctx->uring_lock);
3012 * lock(&ep->mtx);
3013 *
3014 * Users may get EPOLLIN meanwhile seeing nothing in cqring, this
3015 * pushes them to do the flush.
3016 */
3017
3018 if (__io_cqring_events_user(ctx) || io_has_work(ctx))
3019 mask |= EPOLLIN | EPOLLRDNORM;
3020
3021 return mask;
3022 }
3023
io_unregister_personality(struct io_ring_ctx * ctx,unsigned id)3024 static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
3025 {
3026 const struct cred *creds;
3027
3028 creds = xa_erase(&ctx->personalities, id);
3029 if (creds) {
3030 put_cred(creds);
3031 return 0;
3032 }
3033
3034 return -EINVAL;
3035 }
3036
3037 struct io_tctx_exit {
3038 struct callback_head task_work;
3039 struct completion completion;
3040 struct io_ring_ctx *ctx;
3041 };
3042
io_tctx_exit_cb(struct callback_head * cb)3043 static __cold void io_tctx_exit_cb(struct callback_head *cb)
3044 {
3045 struct io_uring_task *tctx = current->io_uring;
3046 struct io_tctx_exit *work;
3047
3048 work = container_of(cb, struct io_tctx_exit, task_work);
3049 /*
3050 * When @in_cancel, we're in cancellation and it's racy to remove the
3051 * node. It'll be removed by the end of cancellation, just ignore it.
3052 * tctx can be NULL if the queueing of this task_work raced with
3053 * work cancelation off the exec path.
3054 */
3055 if (tctx && !atomic_read(&tctx->in_cancel))
3056 io_uring_del_tctx_node((unsigned long)work->ctx);
3057 complete(&work->completion);
3058 }
3059
io_cancel_ctx_cb(struct io_wq_work * work,void * data)3060 static __cold bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
3061 {
3062 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
3063
3064 return req->ctx == data;
3065 }
3066
io_ring_exit_work(struct work_struct * work)3067 static __cold void io_ring_exit_work(struct work_struct *work)
3068 {
3069 struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx, exit_work);
3070 unsigned long timeout = jiffies + HZ * 60 * 5;
3071 unsigned long interval = HZ / 20;
3072 struct io_tctx_exit exit;
3073 struct io_tctx_node *node;
3074 int ret;
3075
3076 /*
3077 * If we're doing polled IO and end up having requests being
3078 * submitted async (out-of-line), then completions can come in while
3079 * we're waiting for refs to drop. We need to reap these manually,
3080 * as nobody else will be looking for them.
3081 */
3082 do {
3083 if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) {
3084 mutex_lock(&ctx->uring_lock);
3085 io_cqring_overflow_kill(ctx);
3086 mutex_unlock(&ctx->uring_lock);
3087 }
3088
3089 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
3090 io_move_task_work_from_local(ctx);
3091
3092 while (io_uring_try_cancel_requests(ctx, NULL, true))
3093 cond_resched();
3094
3095 if (ctx->sq_data) {
3096 struct io_sq_data *sqd = ctx->sq_data;
3097 struct task_struct *tsk;
3098
3099 io_sq_thread_park(sqd);
3100 tsk = sqd->thread;
3101 if (tsk && tsk->io_uring && tsk->io_uring->io_wq)
3102 io_wq_cancel_cb(tsk->io_uring->io_wq,
3103 io_cancel_ctx_cb, ctx, true);
3104 io_sq_thread_unpark(sqd);
3105 }
3106
3107 io_req_caches_free(ctx);
3108
3109 if (WARN_ON_ONCE(time_after(jiffies, timeout))) {
3110 /* there is little hope left, don't run it too often */
3111 interval = HZ * 60;
3112 }
3113 /*
3114 * This is really an uninterruptible wait, as it has to be
3115 * complete. But it's also run from a kworker, which doesn't
3116 * take signals, so it's fine to make it interruptible. This
3117 * avoids scenarios where we knowingly can wait much longer
3118 * on completions, for example if someone does a SIGSTOP on
3119 * a task that needs to finish task_work to make this loop
3120 * complete. That's a synthetic situation that should not
3121 * cause a stuck task backtrace, and hence a potential panic
3122 * on stuck tasks if that is enabled.
3123 */
3124 } while (!wait_for_completion_interruptible_timeout(&ctx->ref_comp, interval));
3125
3126 init_completion(&exit.completion);
3127 init_task_work(&exit.task_work, io_tctx_exit_cb);
3128 exit.ctx = ctx;
3129
3130 mutex_lock(&ctx->uring_lock);
3131 while (!list_empty(&ctx->tctx_list)) {
3132 WARN_ON_ONCE(time_after(jiffies, timeout));
3133
3134 node = list_first_entry(&ctx->tctx_list, struct io_tctx_node,
3135 ctx_node);
3136 /* don't spin on a single task if cancellation failed */
3137 list_rotate_left(&ctx->tctx_list);
3138 ret = task_work_add(node->task, &exit.task_work, TWA_SIGNAL);
3139 if (WARN_ON_ONCE(ret))
3140 continue;
3141
3142 mutex_unlock(&ctx->uring_lock);
3143 /*
3144 * See comment above for
3145 * wait_for_completion_interruptible_timeout() on why this
3146 * wait is marked as interruptible.
3147 */
3148 wait_for_completion_interruptible(&exit.completion);
3149 mutex_lock(&ctx->uring_lock);
3150 }
3151 mutex_unlock(&ctx->uring_lock);
3152 spin_lock(&ctx->completion_lock);
3153 spin_unlock(&ctx->completion_lock);
3154
3155 /* pairs with RCU read section in io_req_local_work_add() */
3156 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
3157 synchronize_rcu();
3158
3159 io_ring_ctx_free(ctx);
3160 }
3161
io_ring_ctx_wait_and_kill(struct io_ring_ctx * ctx)3162 static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
3163 {
3164 unsigned long index;
3165 struct creds *creds;
3166
3167 mutex_lock(&ctx->uring_lock);
3168 percpu_ref_kill(&ctx->refs);
3169 xa_for_each(&ctx->personalities, index, creds)
3170 io_unregister_personality(ctx, index);
3171 if (ctx->rings)
3172 io_poll_remove_all(ctx, NULL, true);
3173 mutex_unlock(&ctx->uring_lock);
3174
3175 /*
3176 * If we failed setting up the ctx, we might not have any rings
3177 * and therefore did not submit any requests
3178 */
3179 if (ctx->rings)
3180 io_kill_timeouts(ctx, NULL, true);
3181
3182 flush_delayed_work(&ctx->fallback_work);
3183
3184 INIT_WORK(&ctx->exit_work, io_ring_exit_work);
3185 /*
3186 * Use system_unbound_wq to avoid spawning tons of event kworkers
3187 * if we're exiting a ton of rings at the same time. It just adds
3188 * noise and overhead, there's no discernable change in runtime
3189 * over using system_wq.
3190 */
3191 queue_work(iou_wq, &ctx->exit_work);
3192 }
3193
io_uring_release(struct inode * inode,struct file * file)3194 static int io_uring_release(struct inode *inode, struct file *file)
3195 {
3196 struct io_ring_ctx *ctx = file->private_data;
3197
3198 file->private_data = NULL;
3199 io_ring_ctx_wait_and_kill(ctx);
3200 return 0;
3201 }
3202
3203 struct io_task_cancel {
3204 struct task_struct *task;
3205 bool all;
3206 };
3207
io_cancel_task_cb(struct io_wq_work * work,void * data)3208 static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
3209 {
3210 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
3211 struct io_task_cancel *cancel = data;
3212
3213 return io_match_task_safe(req, cancel->task, cancel->all);
3214 }
3215
io_cancel_defer_files(struct io_ring_ctx * ctx,struct task_struct * task,bool cancel_all)3216 static __cold bool io_cancel_defer_files(struct io_ring_ctx *ctx,
3217 struct task_struct *task,
3218 bool cancel_all)
3219 {
3220 struct io_defer_entry *de;
3221 LIST_HEAD(list);
3222
3223 spin_lock(&ctx->completion_lock);
3224 list_for_each_entry_reverse(de, &ctx->defer_list, list) {
3225 if (io_match_task_safe(de->req, task, cancel_all)) {
3226 list_cut_position(&list, &ctx->defer_list, &de->list);
3227 break;
3228 }
3229 }
3230 spin_unlock(&ctx->completion_lock);
3231 if (list_empty(&list))
3232 return false;
3233
3234 while (!list_empty(&list)) {
3235 de = list_first_entry(&list, struct io_defer_entry, list);
3236 list_del_init(&de->list);
3237 io_req_task_queue_fail(de->req, -ECANCELED);
3238 kfree(de);
3239 }
3240 return true;
3241 }
3242
io_uring_try_cancel_iowq(struct io_ring_ctx * ctx)3243 static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx)
3244 {
3245 struct io_tctx_node *node;
3246 enum io_wq_cancel cret;
3247 bool ret = false;
3248
3249 mutex_lock(&ctx->uring_lock);
3250 list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
3251 struct io_uring_task *tctx = node->task->io_uring;
3252
3253 /*
3254 * io_wq will stay alive while we hold uring_lock, because it's
3255 * killed after ctx nodes, which requires to take the lock.
3256 */
3257 if (!tctx || !tctx->io_wq)
3258 continue;
3259 cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_ctx_cb, ctx, true);
3260 ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
3261 }
3262 mutex_unlock(&ctx->uring_lock);
3263
3264 return ret;
3265 }
3266
io_uring_try_cancel_requests(struct io_ring_ctx * ctx,struct task_struct * task,bool cancel_all)3267 static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
3268 struct task_struct *task,
3269 bool cancel_all)
3270 {
3271 struct io_task_cancel cancel = { .task = task, .all = cancel_all, };
3272 struct io_uring_task *tctx = task ? task->io_uring : NULL;
3273 enum io_wq_cancel cret;
3274 bool ret = false;
3275
3276 /* set it so io_req_local_work_add() would wake us up */
3277 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
3278 atomic_set(&ctx->cq_wait_nr, 1);
3279 smp_mb();
3280 }
3281
3282 /* failed during ring init, it couldn't have issued any requests */
3283 if (!ctx->rings)
3284 return false;
3285
3286 if (!task) {
3287 ret |= io_uring_try_cancel_iowq(ctx);
3288 } else if (tctx && tctx->io_wq) {
3289 /*
3290 * Cancels requests of all rings, not only @ctx, but
3291 * it's fine as the task is in exit/exec.
3292 */
3293 cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb,
3294 &cancel, true);
3295 ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
3296 }
3297
3298 /* SQPOLL thread does its own polling */
3299 if ((!(ctx->flags & IORING_SETUP_SQPOLL) && cancel_all) ||
3300 (ctx->sq_data && ctx->sq_data->thread == current)) {
3301 while (!wq_list_empty(&ctx->iopoll_list)) {
3302 io_iopoll_try_reap_events(ctx);
3303 ret = true;
3304 cond_resched();
3305 }
3306 }
3307
3308 if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
3309 io_allowed_defer_tw_run(ctx))
3310 ret |= io_run_local_work(ctx, INT_MAX) > 0;
3311 ret |= io_cancel_defer_files(ctx, task, cancel_all);
3312 mutex_lock(&ctx->uring_lock);
3313 ret |= io_poll_remove_all(ctx, task, cancel_all);
3314 mutex_unlock(&ctx->uring_lock);
3315 ret |= io_kill_timeouts(ctx, task, cancel_all);
3316 if (task)
3317 ret |= io_run_task_work() > 0;
3318 return ret;
3319 }
3320
tctx_inflight(struct io_uring_task * tctx,bool tracked)3321 static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
3322 {
3323 if (tracked)
3324 return atomic_read(&tctx->inflight_tracked);
3325 return percpu_counter_sum(&tctx->inflight);
3326 }
3327
3328 /*
3329 * Find any io_uring ctx that this task has registered or done IO on, and cancel
3330 * requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation.
3331 */
io_uring_cancel_generic(bool cancel_all,struct io_sq_data * sqd)3332 __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
3333 {
3334 struct io_uring_task *tctx = current->io_uring;
3335 struct io_ring_ctx *ctx;
3336 struct io_tctx_node *node;
3337 unsigned long index;
3338 s64 inflight;
3339 DEFINE_WAIT(wait);
3340
3341 WARN_ON_ONCE(sqd && sqd->thread != current);
3342
3343 if (!current->io_uring)
3344 return;
3345 if (tctx->io_wq)
3346 io_wq_exit_start(tctx->io_wq);
3347
3348 atomic_inc(&tctx->in_cancel);
3349 do {
3350 bool loop = false;
3351
3352 io_uring_drop_tctx_refs(current);
3353 if (!tctx_inflight(tctx, !cancel_all))
3354 break;
3355
3356 /* read completions before cancelations */
3357 inflight = tctx_inflight(tctx, false);
3358 if (!inflight)
3359 break;
3360
3361 if (!sqd) {
3362 xa_for_each(&tctx->xa, index, node) {
3363 /* sqpoll task will cancel all its requests */
3364 if (node->ctx->sq_data)
3365 continue;
3366 loop |= io_uring_try_cancel_requests(node->ctx,
3367 current, cancel_all);
3368 }
3369 } else {
3370 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
3371 loop |= io_uring_try_cancel_requests(ctx,
3372 current,
3373 cancel_all);
3374 }
3375
3376 if (loop) {
3377 cond_resched();
3378 continue;
3379 }
3380
3381 prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
3382 io_run_task_work();
3383 io_uring_drop_tctx_refs(current);
3384 xa_for_each(&tctx->xa, index, node) {
3385 if (!llist_empty(&node->ctx->work_llist)) {
3386 WARN_ON_ONCE(node->ctx->submitter_task &&
3387 node->ctx->submitter_task != current);
3388 goto end_wait;
3389 }
3390 }
3391 /*
3392 * If we've seen completions, retry without waiting. This
3393 * avoids a race where a completion comes in before we did
3394 * prepare_to_wait().
3395 */
3396 if (inflight == tctx_inflight(tctx, !cancel_all))
3397 schedule();
3398 end_wait:
3399 finish_wait(&tctx->wait, &wait);
3400 } while (1);
3401
3402 io_uring_clean_tctx(tctx);
3403 if (cancel_all) {
3404 /*
3405 * We shouldn't run task_works after cancel, so just leave
3406 * ->in_cancel set for normal exit.
3407 */
3408 atomic_dec(&tctx->in_cancel);
3409 /* for exec all current's requests should be gone, kill tctx */
3410 __io_uring_free(current);
3411 }
3412 }
3413
__io_uring_cancel(bool cancel_all)3414 void __io_uring_cancel(bool cancel_all)
3415 {
3416 io_uring_cancel_generic(cancel_all, NULL);
3417 }
3418
io_uring_validate_mmap_request(struct file * file,loff_t pgoff,size_t sz)3419 static void *io_uring_validate_mmap_request(struct file *file,
3420 loff_t pgoff, size_t sz)
3421 {
3422 struct io_ring_ctx *ctx = file->private_data;
3423 loff_t offset = pgoff << PAGE_SHIFT;
3424 struct page *page;
3425 void *ptr;
3426
3427 switch (offset & IORING_OFF_MMAP_MASK) {
3428 case IORING_OFF_SQ_RING:
3429 case IORING_OFF_CQ_RING:
3430 /* Don't allow mmap if the ring was setup without it */
3431 if (ctx->flags & IORING_SETUP_NO_MMAP)
3432 return ERR_PTR(-EINVAL);
3433 ptr = ctx->rings;
3434 break;
3435 case IORING_OFF_SQES:
3436 /* Don't allow mmap if the ring was setup without it */
3437 if (ctx->flags & IORING_SETUP_NO_MMAP)
3438 return ERR_PTR(-EINVAL);
3439 ptr = ctx->sq_sqes;
3440 break;
3441 case IORING_OFF_PBUF_RING: {
3442 struct io_buffer_list *bl;
3443 unsigned int bgid;
3444
3445 bgid = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
3446 bl = io_pbuf_get_bl(ctx, bgid);
3447 if (IS_ERR(bl))
3448 return bl;
3449 ptr = bl->buf_ring;
3450 io_put_bl(ctx, bl);
3451 break;
3452 }
3453 default:
3454 return ERR_PTR(-EINVAL);
3455 }
3456
3457 page = virt_to_head_page(ptr);
3458 if (sz > page_size(page))
3459 return ERR_PTR(-EINVAL);
3460
3461 return ptr;
3462 }
3463
3464 #ifdef CONFIG_MMU
3465
io_uring_mmap(struct file * file,struct vm_area_struct * vma)3466 static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
3467 {
3468 size_t sz = vma->vm_end - vma->vm_start;
3469 unsigned long pfn;
3470 void *ptr;
3471
3472 ptr = io_uring_validate_mmap_request(file, vma->vm_pgoff, sz);
3473 if (IS_ERR(ptr))
3474 return PTR_ERR(ptr);
3475
3476 pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
3477 return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
3478 }
3479
io_uring_mmu_get_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)3480 static unsigned long io_uring_mmu_get_unmapped_area(struct file *filp,
3481 unsigned long addr, unsigned long len,
3482 unsigned long pgoff, unsigned long flags)
3483 {
3484 void *ptr;
3485
3486 /*
3487 * Do not allow to map to user-provided address to avoid breaking the
3488 * aliasing rules. Userspace is not able to guess the offset address of
3489 * kernel kmalloc()ed memory area.
3490 */
3491 if (addr)
3492 return -EINVAL;
3493
3494 ptr = io_uring_validate_mmap_request(filp, pgoff, len);
3495 if (IS_ERR(ptr))
3496 return -ENOMEM;
3497
3498 /*
3499 * Some architectures have strong cache aliasing requirements.
3500 * For such architectures we need a coherent mapping which aliases
3501 * kernel memory *and* userspace memory. To achieve that:
3502 * - use a NULL file pointer to reference physical memory, and
3503 * - use the kernel virtual address of the shared io_uring context
3504 * (instead of the userspace-provided address, which has to be 0UL
3505 * anyway).
3506 * - use the same pgoff which the get_unmapped_area() uses to
3507 * calculate the page colouring.
3508 * For architectures without such aliasing requirements, the
3509 * architecture will return any suitable mapping because addr is 0.
3510 */
3511 filp = NULL;
3512 flags |= MAP_SHARED;
3513 pgoff = 0; /* has been translated to ptr above */
3514 #ifdef SHM_COLOUR
3515 addr = (uintptr_t) ptr;
3516 pgoff = addr >> PAGE_SHIFT;
3517 #else
3518 addr = 0UL;
3519 #endif
3520 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
3521 }
3522
3523 #else /* !CONFIG_MMU */
3524
io_uring_mmap(struct file * file,struct vm_area_struct * vma)3525 static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
3526 {
3527 return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -EINVAL;
3528 }
3529
io_uring_nommu_mmap_capabilities(struct file * file)3530 static unsigned int io_uring_nommu_mmap_capabilities(struct file *file)
3531 {
3532 return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE;
3533 }
3534
io_uring_nommu_get_unmapped_area(struct file * file,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)3535 static unsigned long io_uring_nommu_get_unmapped_area(struct file *file,
3536 unsigned long addr, unsigned long len,
3537 unsigned long pgoff, unsigned long flags)
3538 {
3539 void *ptr;
3540
3541 ptr = io_uring_validate_mmap_request(file, pgoff, len);
3542 if (IS_ERR(ptr))
3543 return PTR_ERR(ptr);
3544
3545 return (unsigned long) ptr;
3546 }
3547
3548 #endif /* !CONFIG_MMU */
3549
io_validate_ext_arg(unsigned flags,const void __user * argp,size_t argsz)3550 static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t argsz)
3551 {
3552 if (flags & IORING_ENTER_EXT_ARG) {
3553 struct io_uring_getevents_arg arg;
3554
3555 if (argsz != sizeof(arg))
3556 return -EINVAL;
3557 if (copy_from_user(&arg, argp, sizeof(arg)))
3558 return -EFAULT;
3559 }
3560 return 0;
3561 }
3562
io_get_ext_arg(unsigned flags,const void __user * argp,size_t * argsz,struct __kernel_timespec __user ** ts,const sigset_t __user ** sig)3563 static int io_get_ext_arg(unsigned flags, const void __user *argp, size_t *argsz,
3564 struct __kernel_timespec __user **ts,
3565 const sigset_t __user **sig)
3566 {
3567 struct io_uring_getevents_arg arg;
3568
3569 /*
3570 * If EXT_ARG isn't set, then we have no timespec and the argp pointer
3571 * is just a pointer to the sigset_t.
3572 */
3573 if (!(flags & IORING_ENTER_EXT_ARG)) {
3574 *sig = (const sigset_t __user *) argp;
3575 *ts = NULL;
3576 return 0;
3577 }
3578
3579 /*
3580 * EXT_ARG is set - ensure we agree on the size of it and copy in our
3581 * timespec and sigset_t pointers if good.
3582 */
3583 if (*argsz != sizeof(arg))
3584 return -EINVAL;
3585 if (copy_from_user(&arg, argp, sizeof(arg)))
3586 return -EFAULT;
3587 if (arg.pad)
3588 return -EINVAL;
3589 *sig = u64_to_user_ptr(arg.sigmask);
3590 *argsz = arg.sigmask_sz;
3591 *ts = u64_to_user_ptr(arg.ts);
3592 return 0;
3593 }
3594
SYSCALL_DEFINE6(io_uring_enter,unsigned int,fd,u32,to_submit,u32,min_complete,u32,flags,const void __user *,argp,size_t,argsz)3595 SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
3596 u32, min_complete, u32, flags, const void __user *, argp,
3597 size_t, argsz)
3598 {
3599 struct io_ring_ctx *ctx;
3600 struct file *file;
3601 long ret;
3602
3603 if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP |
3604 IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG |
3605 IORING_ENTER_REGISTERED_RING)))
3606 return -EINVAL;
3607
3608 /*
3609 * Ring fd has been registered via IORING_REGISTER_RING_FDS, we
3610 * need only dereference our task private array to find it.
3611 */
3612 if (flags & IORING_ENTER_REGISTERED_RING) {
3613 struct io_uring_task *tctx = current->io_uring;
3614
3615 if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
3616 return -EINVAL;
3617 fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
3618 file = tctx->registered_rings[fd];
3619 if (unlikely(!file))
3620 return -EBADF;
3621 } else {
3622 file = fget(fd);
3623 if (unlikely(!file))
3624 return -EBADF;
3625 ret = -EOPNOTSUPP;
3626 if (unlikely(!io_is_uring_fops(file)))
3627 goto out;
3628 }
3629
3630 ctx = file->private_data;
3631 ret = -EBADFD;
3632 if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED))
3633 goto out;
3634
3635 /*
3636 * For SQ polling, the thread will do all submissions and completions.
3637 * Just return the requested submit count, and wake the thread if
3638 * we were asked to.
3639 */
3640 ret = 0;
3641 if (ctx->flags & IORING_SETUP_SQPOLL) {
3642 io_cqring_overflow_flush(ctx);
3643
3644 if (unlikely(ctx->sq_data->thread == NULL)) {
3645 ret = -EOWNERDEAD;
3646 goto out;
3647 }
3648 if (flags & IORING_ENTER_SQ_WAKEUP)
3649 wake_up(&ctx->sq_data->wait);
3650 if (flags & IORING_ENTER_SQ_WAIT)
3651 io_sqpoll_wait_sq(ctx);
3652
3653 ret = to_submit;
3654 } else if (to_submit) {
3655 ret = io_uring_add_tctx_node(ctx);
3656 if (unlikely(ret))
3657 goto out;
3658
3659 mutex_lock(&ctx->uring_lock);
3660 ret = io_submit_sqes(ctx, to_submit);
3661 if (ret != to_submit) {
3662 mutex_unlock(&ctx->uring_lock);
3663 goto out;
3664 }
3665 if (flags & IORING_ENTER_GETEVENTS) {
3666 if (ctx->syscall_iopoll)
3667 goto iopoll_locked;
3668 /*
3669 * Ignore errors, we'll soon call io_cqring_wait() and
3670 * it should handle ownership problems if any.
3671 */
3672 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
3673 (void)io_run_local_work_locked(ctx, min_complete);
3674 }
3675 mutex_unlock(&ctx->uring_lock);
3676 }
3677
3678 if (flags & IORING_ENTER_GETEVENTS) {
3679 int ret2;
3680
3681 if (ctx->syscall_iopoll) {
3682 /*
3683 * We disallow the app entering submit/complete with
3684 * polling, but we still need to lock the ring to
3685 * prevent racing with polled issue that got punted to
3686 * a workqueue.
3687 */
3688 mutex_lock(&ctx->uring_lock);
3689 iopoll_locked:
3690 ret2 = io_validate_ext_arg(flags, argp, argsz);
3691 if (likely(!ret2)) {
3692 min_complete = min(min_complete,
3693 ctx->cq_entries);
3694 ret2 = io_iopoll_check(ctx, min_complete);
3695 }
3696 mutex_unlock(&ctx->uring_lock);
3697 } else {
3698 const sigset_t __user *sig;
3699 struct __kernel_timespec __user *ts;
3700
3701 ret2 = io_get_ext_arg(flags, argp, &argsz, &ts, &sig);
3702 if (likely(!ret2)) {
3703 min_complete = min(min_complete,
3704 ctx->cq_entries);
3705 ret2 = io_cqring_wait(ctx, min_complete, sig,
3706 argsz, ts);
3707 }
3708 }
3709
3710 if (!ret) {
3711 ret = ret2;
3712
3713 /*
3714 * EBADR indicates that one or more CQE were dropped.
3715 * Once the user has been informed we can clear the bit
3716 * as they are obviously ok with those drops.
3717 */
3718 if (unlikely(ret2 == -EBADR))
3719 clear_bit(IO_CHECK_CQ_DROPPED_BIT,
3720 &ctx->check_cq);
3721 }
3722 }
3723 out:
3724 if (!(flags & IORING_ENTER_REGISTERED_RING))
3725 fput(file);
3726 return ret;
3727 }
3728
3729 static const struct file_operations io_uring_fops = {
3730 .release = io_uring_release,
3731 .mmap = io_uring_mmap,
3732 #ifndef CONFIG_MMU
3733 .get_unmapped_area = io_uring_nommu_get_unmapped_area,
3734 .mmap_capabilities = io_uring_nommu_mmap_capabilities,
3735 #else
3736 .get_unmapped_area = io_uring_mmu_get_unmapped_area,
3737 #endif
3738 .poll = io_uring_poll,
3739 #ifdef CONFIG_PROC_FS
3740 .show_fdinfo = io_uring_show_fdinfo,
3741 #endif
3742 };
3743
io_is_uring_fops(struct file * file)3744 bool io_is_uring_fops(struct file *file)
3745 {
3746 return file->f_op == &io_uring_fops;
3747 }
3748
io_allocate_scq_urings(struct io_ring_ctx * ctx,struct io_uring_params * p)3749 static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
3750 struct io_uring_params *p)
3751 {
3752 struct io_rings *rings;
3753 size_t size, sq_array_offset;
3754 void *ptr;
3755
3756 /* make sure these are sane, as we already accounted them */
3757 ctx->sq_entries = p->sq_entries;
3758 ctx->cq_entries = p->cq_entries;
3759
3760 size = rings_size(ctx, p->sq_entries, p->cq_entries, &sq_array_offset);
3761 if (size == SIZE_MAX)
3762 return -EOVERFLOW;
3763
3764 if (!(ctx->flags & IORING_SETUP_NO_MMAP))
3765 rings = io_mem_alloc(size);
3766 else
3767 rings = io_rings_map(ctx, p->cq_off.user_addr, size);
3768
3769 if (IS_ERR(rings))
3770 return PTR_ERR(rings);
3771
3772 ctx->rings = rings;
3773 if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
3774 ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
3775 rings->sq_ring_mask = p->sq_entries - 1;
3776 rings->cq_ring_mask = p->cq_entries - 1;
3777 rings->sq_ring_entries = p->sq_entries;
3778 rings->cq_ring_entries = p->cq_entries;
3779
3780 if (p->flags & IORING_SETUP_SQE128)
3781 size = array_size(2 * sizeof(struct io_uring_sqe), p->sq_entries);
3782 else
3783 size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
3784 if (size == SIZE_MAX) {
3785 io_rings_free(ctx);
3786 return -EOVERFLOW;
3787 }
3788
3789 if (!(ctx->flags & IORING_SETUP_NO_MMAP))
3790 ptr = io_mem_alloc(size);
3791 else
3792 ptr = io_sqes_map(ctx, p->sq_off.user_addr, size);
3793
3794 if (IS_ERR(ptr)) {
3795 io_rings_free(ctx);
3796 return PTR_ERR(ptr);
3797 }
3798
3799 ctx->sq_sqes = ptr;
3800 return 0;
3801 }
3802
io_uring_install_fd(struct file * file)3803 static int io_uring_install_fd(struct file *file)
3804 {
3805 int fd;
3806
3807 fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
3808 if (fd < 0)
3809 return fd;
3810 fd_install(fd, file);
3811 return fd;
3812 }
3813
3814 /*
3815 * Allocate an anonymous fd, this is what constitutes the application
3816 * visible backing of an io_uring instance. The application mmaps this
3817 * fd to gain access to the SQ/CQ ring details.
3818 */
io_uring_get_file(struct io_ring_ctx * ctx)3819 static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
3820 {
3821 return anon_inode_getfile_secure("[io_uring]", &io_uring_fops, ctx,
3822 O_RDWR | O_CLOEXEC, NULL);
3823 }
3824
io_uring_create(unsigned entries,struct io_uring_params * p,struct io_uring_params __user * params)3825 static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
3826 struct io_uring_params __user *params)
3827 {
3828 struct io_ring_ctx *ctx;
3829 struct io_uring_task *tctx;
3830 struct file *file;
3831 int ret;
3832
3833 if (!entries)
3834 return -EINVAL;
3835 if (entries > IORING_MAX_ENTRIES) {
3836 if (!(p->flags & IORING_SETUP_CLAMP))
3837 return -EINVAL;
3838 entries = IORING_MAX_ENTRIES;
3839 }
3840
3841 if ((p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
3842 && !(p->flags & IORING_SETUP_NO_MMAP))
3843 return -EINVAL;
3844
3845 /*
3846 * Use twice as many entries for the CQ ring. It's possible for the
3847 * application to drive a higher depth than the size of the SQ ring,
3848 * since the sqes are only used at submission time. This allows for
3849 * some flexibility in overcommitting a bit. If the application has
3850 * set IORING_SETUP_CQSIZE, it will have passed in the desired number
3851 * of CQ ring entries manually.
3852 */
3853 p->sq_entries = roundup_pow_of_two(entries);
3854 if (p->flags & IORING_SETUP_CQSIZE) {
3855 /*
3856 * If IORING_SETUP_CQSIZE is set, we do the same roundup
3857 * to a power-of-two, if it isn't already. We do NOT impose
3858 * any cq vs sq ring sizing.
3859 */
3860 if (!p->cq_entries)
3861 return -EINVAL;
3862 if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
3863 if (!(p->flags & IORING_SETUP_CLAMP))
3864 return -EINVAL;
3865 p->cq_entries = IORING_MAX_CQ_ENTRIES;
3866 }
3867 p->cq_entries = roundup_pow_of_two(p->cq_entries);
3868 if (p->cq_entries < p->sq_entries)
3869 return -EINVAL;
3870 } else {
3871 p->cq_entries = 2 * p->sq_entries;
3872 }
3873
3874 ctx = io_ring_ctx_alloc(p);
3875 if (!ctx)
3876 return -ENOMEM;
3877
3878 if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
3879 !(ctx->flags & IORING_SETUP_IOPOLL) &&
3880 !(ctx->flags & IORING_SETUP_SQPOLL))
3881 ctx->task_complete = true;
3882
3883 if (ctx->task_complete || (ctx->flags & IORING_SETUP_IOPOLL))
3884 ctx->lockless_cq = true;
3885
3886 /*
3887 * lazy poll_wq activation relies on ->task_complete for synchronisation
3888 * purposes, see io_activate_pollwq()
3889 */
3890 if (!ctx->task_complete)
3891 ctx->poll_activated = true;
3892
3893 /*
3894 * When SETUP_IOPOLL and SETUP_SQPOLL are both enabled, user
3895 * space applications don't need to do io completion events
3896 * polling again, they can rely on io_sq_thread to do polling
3897 * work, which can reduce cpu usage and uring_lock contention.
3898 */
3899 if (ctx->flags & IORING_SETUP_IOPOLL &&
3900 !(ctx->flags & IORING_SETUP_SQPOLL))
3901 ctx->syscall_iopoll = 1;
3902
3903 ctx->compat = in_compat_syscall();
3904 if (!ns_capable_noaudit(&init_user_ns, CAP_IPC_LOCK))
3905 ctx->user = get_uid(current_user());
3906
3907 /*
3908 * For SQPOLL, we just need a wakeup, always. For !SQPOLL, if
3909 * COOP_TASKRUN is set, then IPIs are never needed by the app.
3910 */
3911 ret = -EINVAL;
3912 if (ctx->flags & IORING_SETUP_SQPOLL) {
3913 /* IPI related flags don't make sense with SQPOLL */
3914 if (ctx->flags & (IORING_SETUP_COOP_TASKRUN |
3915 IORING_SETUP_TASKRUN_FLAG |
3916 IORING_SETUP_DEFER_TASKRUN))
3917 goto err;
3918 ctx->notify_method = TWA_SIGNAL_NO_IPI;
3919 } else if (ctx->flags & IORING_SETUP_COOP_TASKRUN) {
3920 ctx->notify_method = TWA_SIGNAL_NO_IPI;
3921 } else {
3922 if (ctx->flags & IORING_SETUP_TASKRUN_FLAG &&
3923 !(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
3924 goto err;
3925 ctx->notify_method = TWA_SIGNAL;
3926 }
3927
3928 /*
3929 * For DEFER_TASKRUN we require the completion task to be the same as the
3930 * submission task. This implies that there is only one submitter, so enforce
3931 * that.
3932 */
3933 if (ctx->flags & IORING_SETUP_DEFER_TASKRUN &&
3934 !(ctx->flags & IORING_SETUP_SINGLE_ISSUER)) {
3935 goto err;
3936 }
3937
3938 /*
3939 * This is just grabbed for accounting purposes. When a process exits,
3940 * the mm is exited and dropped before the files, hence we need to hang
3941 * on to this mm purely for the purposes of being able to unaccount
3942 * memory (locked/pinned vm). It's not used for anything else.
3943 */
3944 mmgrab(current->mm);
3945 ctx->mm_account = current->mm;
3946
3947 ret = io_allocate_scq_urings(ctx, p);
3948 if (ret)
3949 goto err;
3950
3951 ret = io_sq_offload_create(ctx, p);
3952 if (ret)
3953 goto err;
3954
3955 ret = io_rsrc_init(ctx);
3956 if (ret)
3957 goto err;
3958
3959 p->sq_off.head = offsetof(struct io_rings, sq.head);
3960 p->sq_off.tail = offsetof(struct io_rings, sq.tail);
3961 p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
3962 p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
3963 p->sq_off.flags = offsetof(struct io_rings, sq_flags);
3964 p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
3965 if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
3966 p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
3967 p->sq_off.resv1 = 0;
3968 if (!(ctx->flags & IORING_SETUP_NO_MMAP))
3969 p->sq_off.user_addr = 0;
3970
3971 p->cq_off.head = offsetof(struct io_rings, cq.head);
3972 p->cq_off.tail = offsetof(struct io_rings, cq.tail);
3973 p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
3974 p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
3975 p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
3976 p->cq_off.cqes = offsetof(struct io_rings, cqes);
3977 p->cq_off.flags = offsetof(struct io_rings, cq_flags);
3978 p->cq_off.resv1 = 0;
3979 if (!(ctx->flags & IORING_SETUP_NO_MMAP))
3980 p->cq_off.user_addr = 0;
3981
3982 p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
3983 IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
3984 IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL |
3985 IORING_FEAT_POLL_32BITS | IORING_FEAT_SQPOLL_NONFIXED |
3986 IORING_FEAT_EXT_ARG | IORING_FEAT_NATIVE_WORKERS |
3987 IORING_FEAT_RSRC_TAGS | IORING_FEAT_CQE_SKIP |
3988 IORING_FEAT_LINKED_FILE | IORING_FEAT_REG_REG_RING;
3989
3990 if (copy_to_user(params, p, sizeof(*p))) {
3991 ret = -EFAULT;
3992 goto err;
3993 }
3994
3995 if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
3996 && !(ctx->flags & IORING_SETUP_R_DISABLED))
3997 WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
3998
3999 file = io_uring_get_file(ctx);
4000 if (IS_ERR(file)) {
4001 ret = PTR_ERR(file);
4002 goto err;
4003 }
4004
4005 ret = __io_uring_add_tctx_node(ctx);
4006 if (ret)
4007 goto err_fput;
4008 tctx = current->io_uring;
4009
4010 /*
4011 * Install ring fd as the very last thing, so we don't risk someone
4012 * having closed it before we finish setup
4013 */
4014 if (p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
4015 ret = io_ring_add_registered_file(tctx, file, 0, IO_RINGFD_REG_MAX);
4016 else
4017 ret = io_uring_install_fd(file);
4018 if (ret < 0)
4019 goto err_fput;
4020
4021 trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);
4022 return ret;
4023 err:
4024 io_ring_ctx_wait_and_kill(ctx);
4025 return ret;
4026 err_fput:
4027 fput(file);
4028 return ret;
4029 }
4030
4031 /*
4032 * Sets up an aio uring context, and returns the fd. Applications asks for a
4033 * ring size, we return the actual sq/cq ring sizes (among other things) in the
4034 * params structure passed in.
4035 */
io_uring_setup(u32 entries,struct io_uring_params __user * params)4036 static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
4037 {
4038 struct io_uring_params p;
4039 int i;
4040
4041 if (copy_from_user(&p, params, sizeof(p)))
4042 return -EFAULT;
4043 for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
4044 if (p.resv[i])
4045 return -EINVAL;
4046 }
4047
4048 if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
4049 IORING_SETUP_SQ_AFF | IORING_SETUP_CQSIZE |
4050 IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
4051 IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
4052 IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
4053 IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
4054 IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN |
4055 IORING_SETUP_NO_MMAP | IORING_SETUP_REGISTERED_FD_ONLY |
4056 IORING_SETUP_NO_SQARRAY))
4057 return -EINVAL;
4058
4059 return io_uring_create(entries, &p, params);
4060 }
4061
io_uring_allowed(void)4062 static inline bool io_uring_allowed(void)
4063 {
4064 int disabled = READ_ONCE(sysctl_io_uring_disabled);
4065 kgid_t io_uring_group;
4066
4067 if (disabled == 2)
4068 return false;
4069
4070 if (disabled == 0 || capable(CAP_SYS_ADMIN))
4071 return true;
4072
4073 io_uring_group = make_kgid(&init_user_ns, sysctl_io_uring_group);
4074 if (!gid_valid(io_uring_group))
4075 return false;
4076
4077 return in_group_p(io_uring_group);
4078 }
4079
SYSCALL_DEFINE2(io_uring_setup,u32,entries,struct io_uring_params __user *,params)4080 SYSCALL_DEFINE2(io_uring_setup, u32, entries,
4081 struct io_uring_params __user *, params)
4082 {
4083 if (!io_uring_allowed())
4084 return -EPERM;
4085
4086 return io_uring_setup(entries, params);
4087 }
4088
io_probe(struct io_ring_ctx * ctx,void __user * arg,unsigned nr_args)4089 static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg,
4090 unsigned nr_args)
4091 {
4092 struct io_uring_probe *p;
4093 size_t size;
4094 int i, ret;
4095
4096 size = struct_size(p, ops, nr_args);
4097 if (size == SIZE_MAX)
4098 return -EOVERFLOW;
4099 p = kzalloc(size, GFP_KERNEL);
4100 if (!p)
4101 return -ENOMEM;
4102
4103 ret = -EFAULT;
4104 if (copy_from_user(p, arg, size))
4105 goto out;
4106 ret = -EINVAL;
4107 if (memchr_inv(p, 0, size))
4108 goto out;
4109
4110 p->last_op = IORING_OP_LAST - 1;
4111 if (nr_args > IORING_OP_LAST)
4112 nr_args = IORING_OP_LAST;
4113
4114 for (i = 0; i < nr_args; i++) {
4115 p->ops[i].op = i;
4116 if (!io_issue_defs[i].not_supported)
4117 p->ops[i].flags = IO_URING_OP_SUPPORTED;
4118 }
4119 p->ops_len = i;
4120
4121 ret = 0;
4122 if (copy_to_user(arg, p, size))
4123 ret = -EFAULT;
4124 out:
4125 kfree(p);
4126 return ret;
4127 }
4128
io_register_personality(struct io_ring_ctx * ctx)4129 static int io_register_personality(struct io_ring_ctx *ctx)
4130 {
4131 const struct cred *creds;
4132 u32 id;
4133 int ret;
4134
4135 creds = get_current_cred();
4136
4137 ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
4138 XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
4139 if (ret < 0) {
4140 put_cred(creds);
4141 return ret;
4142 }
4143 return id;
4144 }
4145
io_register_restrictions(struct io_ring_ctx * ctx,void __user * arg,unsigned int nr_args)4146 static __cold int io_register_restrictions(struct io_ring_ctx *ctx,
4147 void __user *arg, unsigned int nr_args)
4148 {
4149 struct io_uring_restriction *res;
4150 size_t size;
4151 int i, ret;
4152
4153 /* Restrictions allowed only if rings started disabled */
4154 if (!(ctx->flags & IORING_SETUP_R_DISABLED))
4155 return -EBADFD;
4156
4157 /* We allow only a single restrictions registration */
4158 if (ctx->restrictions.registered)
4159 return -EBUSY;
4160
4161 if (!arg || nr_args > IORING_MAX_RESTRICTIONS)
4162 return -EINVAL;
4163
4164 size = array_size(nr_args, sizeof(*res));
4165 if (size == SIZE_MAX)
4166 return -EOVERFLOW;
4167
4168 res = memdup_user(arg, size);
4169 if (IS_ERR(res))
4170 return PTR_ERR(res);
4171
4172 ret = 0;
4173
4174 for (i = 0; i < nr_args; i++) {
4175 switch (res[i].opcode) {
4176 case IORING_RESTRICTION_REGISTER_OP:
4177 if (res[i].register_op >= IORING_REGISTER_LAST) {
4178 ret = -EINVAL;
4179 goto out;
4180 }
4181
4182 __set_bit(res[i].register_op,
4183 ctx->restrictions.register_op);
4184 break;
4185 case IORING_RESTRICTION_SQE_OP:
4186 if (res[i].sqe_op >= IORING_OP_LAST) {
4187 ret = -EINVAL;
4188 goto out;
4189 }
4190
4191 __set_bit(res[i].sqe_op, ctx->restrictions.sqe_op);
4192 break;
4193 case IORING_RESTRICTION_SQE_FLAGS_ALLOWED:
4194 ctx->restrictions.sqe_flags_allowed = res[i].sqe_flags;
4195 break;
4196 case IORING_RESTRICTION_SQE_FLAGS_REQUIRED:
4197 ctx->restrictions.sqe_flags_required = res[i].sqe_flags;
4198 break;
4199 default:
4200 ret = -EINVAL;
4201 goto out;
4202 }
4203 }
4204
4205 out:
4206 /* Reset all restrictions if an error happened */
4207 if (ret != 0)
4208 memset(&ctx->restrictions, 0, sizeof(ctx->restrictions));
4209 else
4210 ctx->restrictions.registered = true;
4211
4212 kfree(res);
4213 return ret;
4214 }
4215
io_register_enable_rings(struct io_ring_ctx * ctx)4216 static int io_register_enable_rings(struct io_ring_ctx *ctx)
4217 {
4218 if (!(ctx->flags & IORING_SETUP_R_DISABLED))
4219 return -EBADFD;
4220
4221 if (ctx->flags & IORING_SETUP_SINGLE_ISSUER && !ctx->submitter_task) {
4222 WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
4223 /*
4224 * Lazy activation attempts would fail if it was polled before
4225 * submitter_task is set.
4226 */
4227 if (wq_has_sleeper(&ctx->poll_wq))
4228 io_activate_pollwq(ctx);
4229 }
4230
4231 if (ctx->restrictions.registered)
4232 ctx->restricted = 1;
4233
4234 ctx->flags &= ~IORING_SETUP_R_DISABLED;
4235 if (ctx->sq_data && wq_has_sleeper(&ctx->sq_data->wait))
4236 wake_up(&ctx->sq_data->wait);
4237 return 0;
4238 }
4239
__io_register_iowq_aff(struct io_ring_ctx * ctx,cpumask_var_t new_mask)4240 static __cold int __io_register_iowq_aff(struct io_ring_ctx *ctx,
4241 cpumask_var_t new_mask)
4242 {
4243 int ret;
4244
4245 if (!(ctx->flags & IORING_SETUP_SQPOLL)) {
4246 ret = io_wq_cpu_affinity(current->io_uring, new_mask);
4247 } else {
4248 mutex_unlock(&ctx->uring_lock);
4249 ret = io_sqpoll_wq_cpu_affinity(ctx, new_mask);
4250 mutex_lock(&ctx->uring_lock);
4251 }
4252
4253 return ret;
4254 }
4255
io_register_iowq_aff(struct io_ring_ctx * ctx,void __user * arg,unsigned len)4256 static __cold int io_register_iowq_aff(struct io_ring_ctx *ctx,
4257 void __user *arg, unsigned len)
4258 {
4259 cpumask_var_t new_mask;
4260 int ret;
4261
4262 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4263 return -ENOMEM;
4264
4265 cpumask_clear(new_mask);
4266 if (len > cpumask_size())
4267 len = cpumask_size();
4268
4269 if (in_compat_syscall()) {
4270 ret = compat_get_bitmap(cpumask_bits(new_mask),
4271 (const compat_ulong_t __user *)arg,
4272 len * 8 /* CHAR_BIT */);
4273 } else {
4274 ret = copy_from_user(new_mask, arg, len);
4275 }
4276
4277 if (ret) {
4278 free_cpumask_var(new_mask);
4279 return -EFAULT;
4280 }
4281
4282 ret = __io_register_iowq_aff(ctx, new_mask);
4283 free_cpumask_var(new_mask);
4284 return ret;
4285 }
4286
io_unregister_iowq_aff(struct io_ring_ctx * ctx)4287 static __cold int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
4288 {
4289 return __io_register_iowq_aff(ctx, NULL);
4290 }
4291
io_register_iowq_max_workers(struct io_ring_ctx * ctx,void __user * arg)4292 static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
4293 void __user *arg)
4294 __must_hold(&ctx->uring_lock)
4295 {
4296 struct io_tctx_node *node;
4297 struct io_uring_task *tctx = NULL;
4298 struct io_sq_data *sqd = NULL;
4299 __u32 new_count[2];
4300 int i, ret;
4301
4302 if (copy_from_user(new_count, arg, sizeof(new_count)))
4303 return -EFAULT;
4304 for (i = 0; i < ARRAY_SIZE(new_count); i++)
4305 if (new_count[i] > INT_MAX)
4306 return -EINVAL;
4307
4308 if (ctx->flags & IORING_SETUP_SQPOLL) {
4309 sqd = ctx->sq_data;
4310 if (sqd) {
4311 /*
4312 * Observe the correct sqd->lock -> ctx->uring_lock
4313 * ordering. Fine to drop uring_lock here, we hold
4314 * a ref to the ctx.
4315 */
4316 refcount_inc(&sqd->refs);
4317 mutex_unlock(&ctx->uring_lock);
4318 mutex_lock(&sqd->lock);
4319 mutex_lock(&ctx->uring_lock);
4320 if (sqd->thread)
4321 tctx = sqd->thread->io_uring;
4322 }
4323 } else {
4324 tctx = current->io_uring;
4325 }
4326
4327 BUILD_BUG_ON(sizeof(new_count) != sizeof(ctx->iowq_limits));
4328
4329 for (i = 0; i < ARRAY_SIZE(new_count); i++)
4330 if (new_count[i])
4331 ctx->iowq_limits[i] = new_count[i];
4332 ctx->iowq_limits_set = true;
4333
4334 if (tctx && tctx->io_wq) {
4335 ret = io_wq_max_workers(tctx->io_wq, new_count);
4336 if (ret)
4337 goto err;
4338 } else {
4339 memset(new_count, 0, sizeof(new_count));
4340 }
4341
4342 if (sqd) {
4343 mutex_unlock(&sqd->lock);
4344 io_put_sq_data(sqd);
4345 }
4346
4347 if (copy_to_user(arg, new_count, sizeof(new_count)))
4348 return -EFAULT;
4349
4350 /* that's it for SQPOLL, only the SQPOLL task creates requests */
4351 if (sqd)
4352 return 0;
4353
4354 /* now propagate the restriction to all registered users */
4355 list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
4356 struct io_uring_task *tctx = node->task->io_uring;
4357
4358 if (WARN_ON_ONCE(!tctx->io_wq))
4359 continue;
4360
4361 for (i = 0; i < ARRAY_SIZE(new_count); i++)
4362 new_count[i] = ctx->iowq_limits[i];
4363 /* ignore errors, it always returns zero anyway */
4364 (void)io_wq_max_workers(tctx->io_wq, new_count);
4365 }
4366 return 0;
4367 err:
4368 if (sqd) {
4369 mutex_unlock(&sqd->lock);
4370 io_put_sq_data(sqd);
4371 }
4372 return ret;
4373 }
4374
__io_uring_register(struct io_ring_ctx * ctx,unsigned opcode,void __user * arg,unsigned nr_args)4375 static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
4376 void __user *arg, unsigned nr_args)
4377 __releases(ctx->uring_lock)
4378 __acquires(ctx->uring_lock)
4379 {
4380 int ret;
4381
4382 /*
4383 * We don't quiesce the refs for register anymore and so it can't be
4384 * dying as we're holding a file ref here.
4385 */
4386 if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
4387 return -ENXIO;
4388
4389 if (ctx->submitter_task && ctx->submitter_task != current)
4390 return -EEXIST;
4391
4392 if (ctx->restricted) {
4393 opcode = array_index_nospec(opcode, IORING_REGISTER_LAST);
4394 if (!test_bit(opcode, ctx->restrictions.register_op))
4395 return -EACCES;
4396 }
4397
4398 switch (opcode) {
4399 case IORING_REGISTER_BUFFERS:
4400 ret = -EFAULT;
4401 if (!arg)
4402 break;
4403 ret = io_sqe_buffers_register(ctx, arg, nr_args, NULL);
4404 break;
4405 case IORING_UNREGISTER_BUFFERS:
4406 ret = -EINVAL;
4407 if (arg || nr_args)
4408 break;
4409 ret = io_sqe_buffers_unregister(ctx);
4410 break;
4411 case IORING_REGISTER_FILES:
4412 ret = -EFAULT;
4413 if (!arg)
4414 break;
4415 ret = io_sqe_files_register(ctx, arg, nr_args, NULL);
4416 break;
4417 case IORING_UNREGISTER_FILES:
4418 ret = -EINVAL;
4419 if (arg || nr_args)
4420 break;
4421 ret = io_sqe_files_unregister(ctx);
4422 break;
4423 case IORING_REGISTER_FILES_UPDATE:
4424 ret = io_register_files_update(ctx, arg, nr_args);
4425 break;
4426 case IORING_REGISTER_EVENTFD:
4427 ret = -EINVAL;
4428 if (nr_args != 1)
4429 break;
4430 ret = io_eventfd_register(ctx, arg, 0);
4431 break;
4432 case IORING_REGISTER_EVENTFD_ASYNC:
4433 ret = -EINVAL;
4434 if (nr_args != 1)
4435 break;
4436 ret = io_eventfd_register(ctx, arg, 1);
4437 break;
4438 case IORING_UNREGISTER_EVENTFD:
4439 ret = -EINVAL;
4440 if (arg || nr_args)
4441 break;
4442 ret = io_eventfd_unregister(ctx);
4443 break;
4444 case IORING_REGISTER_PROBE:
4445 ret = -EINVAL;
4446 if (!arg || nr_args > 256)
4447 break;
4448 ret = io_probe(ctx, arg, nr_args);
4449 break;
4450 case IORING_REGISTER_PERSONALITY:
4451 ret = -EINVAL;
4452 if (arg || nr_args)
4453 break;
4454 ret = io_register_personality(ctx);
4455 break;
4456 case IORING_UNREGISTER_PERSONALITY:
4457 ret = -EINVAL;
4458 if (arg)
4459 break;
4460 ret = io_unregister_personality(ctx, nr_args);
4461 break;
4462 case IORING_REGISTER_ENABLE_RINGS:
4463 ret = -EINVAL;
4464 if (arg || nr_args)
4465 break;
4466 ret = io_register_enable_rings(ctx);
4467 break;
4468 case IORING_REGISTER_RESTRICTIONS:
4469 ret = io_register_restrictions(ctx, arg, nr_args);
4470 break;
4471 case IORING_REGISTER_FILES2:
4472 ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_FILE);
4473 break;
4474 case IORING_REGISTER_FILES_UPDATE2:
4475 ret = io_register_rsrc_update(ctx, arg, nr_args,
4476 IORING_RSRC_FILE);
4477 break;
4478 case IORING_REGISTER_BUFFERS2:
4479 ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_BUFFER);
4480 break;
4481 case IORING_REGISTER_BUFFERS_UPDATE:
4482 ret = io_register_rsrc_update(ctx, arg, nr_args,
4483 IORING_RSRC_BUFFER);
4484 break;
4485 case IORING_REGISTER_IOWQ_AFF:
4486 ret = -EINVAL;
4487 if (!arg || !nr_args)
4488 break;
4489 ret = io_register_iowq_aff(ctx, arg, nr_args);
4490 break;
4491 case IORING_UNREGISTER_IOWQ_AFF:
4492 ret = -EINVAL;
4493 if (arg || nr_args)
4494 break;
4495 ret = io_unregister_iowq_aff(ctx);
4496 break;
4497 case IORING_REGISTER_IOWQ_MAX_WORKERS:
4498 ret = -EINVAL;
4499 if (!arg || nr_args != 2)
4500 break;
4501 ret = io_register_iowq_max_workers(ctx, arg);
4502 break;
4503 case IORING_REGISTER_RING_FDS:
4504 ret = io_ringfd_register(ctx, arg, nr_args);
4505 break;
4506 case IORING_UNREGISTER_RING_FDS:
4507 ret = io_ringfd_unregister(ctx, arg, nr_args);
4508 break;
4509 case IORING_REGISTER_PBUF_RING:
4510 ret = -EINVAL;
4511 if (!arg || nr_args != 1)
4512 break;
4513 ret = io_register_pbuf_ring(ctx, arg);
4514 break;
4515 case IORING_UNREGISTER_PBUF_RING:
4516 ret = -EINVAL;
4517 if (!arg || nr_args != 1)
4518 break;
4519 ret = io_unregister_pbuf_ring(ctx, arg);
4520 break;
4521 case IORING_REGISTER_SYNC_CANCEL:
4522 ret = -EINVAL;
4523 if (!arg || nr_args != 1)
4524 break;
4525 ret = io_sync_cancel(ctx, arg);
4526 break;
4527 case IORING_REGISTER_FILE_ALLOC_RANGE:
4528 ret = -EINVAL;
4529 if (!arg || nr_args)
4530 break;
4531 ret = io_register_file_alloc_range(ctx, arg);
4532 break;
4533 default:
4534 ret = -EINVAL;
4535 break;
4536 }
4537
4538 return ret;
4539 }
4540
SYSCALL_DEFINE4(io_uring_register,unsigned int,fd,unsigned int,opcode,void __user *,arg,unsigned int,nr_args)4541 SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
4542 void __user *, arg, unsigned int, nr_args)
4543 {
4544 struct io_ring_ctx *ctx;
4545 long ret = -EBADF;
4546 struct file *file;
4547 bool use_registered_ring;
4548
4549 use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);
4550 opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
4551
4552 if (opcode >= IORING_REGISTER_LAST)
4553 return -EINVAL;
4554
4555 if (use_registered_ring) {
4556 /*
4557 * Ring fd has been registered via IORING_REGISTER_RING_FDS, we
4558 * need only dereference our task private array to find it.
4559 */
4560 struct io_uring_task *tctx = current->io_uring;
4561
4562 if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
4563 return -EINVAL;
4564 fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
4565 file = tctx->registered_rings[fd];
4566 if (unlikely(!file))
4567 return -EBADF;
4568 } else {
4569 file = fget(fd);
4570 if (unlikely(!file))
4571 return -EBADF;
4572 ret = -EOPNOTSUPP;
4573 if (!io_is_uring_fops(file))
4574 goto out_fput;
4575 }
4576
4577 ctx = file->private_data;
4578
4579 mutex_lock(&ctx->uring_lock);
4580 ret = __io_uring_register(ctx, opcode, arg, nr_args);
4581 mutex_unlock(&ctx->uring_lock);
4582 trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret);
4583 out_fput:
4584 if (!use_registered_ring)
4585 fput(file);
4586 return ret;
4587 }
4588
io_uring_init(void)4589 static int __init io_uring_init(void)
4590 {
4591 #define __BUILD_BUG_VERIFY_OFFSET_SIZE(stype, eoffset, esize, ename) do { \
4592 BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
4593 BUILD_BUG_ON(sizeof_field(stype, ename) != esize); \
4594 } while (0)
4595
4596 #define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
4597 __BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, sizeof(etype), ename)
4598 #define BUILD_BUG_SQE_ELEM_SIZE(eoffset, esize, ename) \
4599 __BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, esize, ename)
4600 BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
4601 BUILD_BUG_SQE_ELEM(0, __u8, opcode);
4602 BUILD_BUG_SQE_ELEM(1, __u8, flags);
4603 BUILD_BUG_SQE_ELEM(2, __u16, ioprio);
4604 BUILD_BUG_SQE_ELEM(4, __s32, fd);
4605 BUILD_BUG_SQE_ELEM(8, __u64, off);
4606 BUILD_BUG_SQE_ELEM(8, __u64, addr2);
4607 BUILD_BUG_SQE_ELEM(8, __u32, cmd_op);
4608 BUILD_BUG_SQE_ELEM(12, __u32, __pad1);
4609 BUILD_BUG_SQE_ELEM(16, __u64, addr);
4610 BUILD_BUG_SQE_ELEM(16, __u64, splice_off_in);
4611 BUILD_BUG_SQE_ELEM(24, __u32, len);
4612 BUILD_BUG_SQE_ELEM(28, __kernel_rwf_t, rw_flags);
4613 BUILD_BUG_SQE_ELEM(28, /* compat */ int, rw_flags);
4614 BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
4615 BUILD_BUG_SQE_ELEM(28, __u32, fsync_flags);
4616 BUILD_BUG_SQE_ELEM(28, /* compat */ __u16, poll_events);
4617 BUILD_BUG_SQE_ELEM(28, __u32, poll32_events);
4618 BUILD_BUG_SQE_ELEM(28, __u32, sync_range_flags);
4619 BUILD_BUG_SQE_ELEM(28, __u32, msg_flags);
4620 BUILD_BUG_SQE_ELEM(28, __u32, timeout_flags);
4621 BUILD_BUG_SQE_ELEM(28, __u32, accept_flags);
4622 BUILD_BUG_SQE_ELEM(28, __u32, cancel_flags);
4623 BUILD_BUG_SQE_ELEM(28, __u32, open_flags);
4624 BUILD_BUG_SQE_ELEM(28, __u32, statx_flags);
4625 BUILD_BUG_SQE_ELEM(28, __u32, fadvise_advice);
4626 BUILD_BUG_SQE_ELEM(28, __u32, splice_flags);
4627 BUILD_BUG_SQE_ELEM(28, __u32, rename_flags);
4628 BUILD_BUG_SQE_ELEM(28, __u32, unlink_flags);
4629 BUILD_BUG_SQE_ELEM(28, __u32, hardlink_flags);
4630 BUILD_BUG_SQE_ELEM(28, __u32, xattr_flags);
4631 BUILD_BUG_SQE_ELEM(28, __u32, msg_ring_flags);
4632 BUILD_BUG_SQE_ELEM(32, __u64, user_data);
4633 BUILD_BUG_SQE_ELEM(40, __u16, buf_index);
4634 BUILD_BUG_SQE_ELEM(40, __u16, buf_group);
4635 BUILD_BUG_SQE_ELEM(42, __u16, personality);
4636 BUILD_BUG_SQE_ELEM(44, __s32, splice_fd_in);
4637 BUILD_BUG_SQE_ELEM(44, __u32, file_index);
4638 BUILD_BUG_SQE_ELEM(44, __u16, addr_len);
4639 BUILD_BUG_SQE_ELEM(46, __u16, __pad3[0]);
4640 BUILD_BUG_SQE_ELEM(48, __u64, addr3);
4641 BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
4642 BUILD_BUG_SQE_ELEM(56, __u64, __pad2);
4643
4644 BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
4645 sizeof(struct io_uring_rsrc_update));
4646 BUILD_BUG_ON(sizeof(struct io_uring_rsrc_update) >
4647 sizeof(struct io_uring_rsrc_update2));
4648
4649 /* ->buf_index is u16 */
4650 BUILD_BUG_ON(offsetof(struct io_uring_buf_ring, bufs) != 0);
4651 BUILD_BUG_ON(offsetof(struct io_uring_buf, resv) !=
4652 offsetof(struct io_uring_buf_ring, tail));
4653
4654 /* should fit into one byte */
4655 BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
4656 BUILD_BUG_ON(SQE_COMMON_FLAGS >= (1 << 8));
4657 BUILD_BUG_ON((SQE_VALID_FLAGS | SQE_COMMON_FLAGS) != SQE_VALID_FLAGS);
4658
4659 BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int));
4660
4661 BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32));
4662
4663 io_uring_optable_init();
4664
4665 /*
4666 * Allow user copy in the per-command field, which starts after the
4667 * file in io_kiocb and until the opcode field. The openat2 handling
4668 * requires copying in user memory into the io_kiocb object in that
4669 * range, and HARDENED_USERCOPY will complain if we haven't
4670 * correctly annotated this range.
4671 */
4672 req_cachep = kmem_cache_create_usercopy("io_kiocb",
4673 sizeof(struct io_kiocb), 0,
4674 SLAB_HWCACHE_ALIGN | SLAB_PANIC |
4675 SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU,
4676 offsetof(struct io_kiocb, cmd.data),
4677 sizeof_field(struct io_kiocb, cmd.data), NULL);
4678
4679 iou_wq = alloc_workqueue("iou_exit", WQ_UNBOUND, 64);
4680
4681 #ifdef CONFIG_SYSCTL
4682 register_sysctl_init("kernel", kernel_io_uring_disabled_table);
4683 #endif
4684
4685 return 0;
4686 };
4687 __initcall(io_uring_init);
4688