xref: /openbmc/linux/io_uring/tctx.c (revision 8a0a6c9af053fb93c0edf4581518c77fd131803e)
1  // SPDX-License-Identifier: GPL-2.0
2  #include <linux/kernel.h>
3  #include <linux/errno.h>
4  #include <linux/file.h>
5  #include <linux/mm.h>
6  #include <linux/slab.h>
7  #include <linux/nospec.h>
8  #include <linux/io_uring.h>
9  
10  #include <uapi/linux/io_uring.h>
11  
12  #include "io_uring.h"
13  #include "tctx.h"
14  
15  static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
16  					struct task_struct *task)
17  {
18  	struct io_wq_hash *hash;
19  	struct io_wq_data data;
20  	unsigned int concurrency;
21  
22  	mutex_lock(&ctx->uring_lock);
23  	hash = ctx->hash_map;
24  	if (!hash) {
25  		hash = kzalloc(sizeof(*hash), GFP_KERNEL);
26  		if (!hash) {
27  			mutex_unlock(&ctx->uring_lock);
28  			return ERR_PTR(-ENOMEM);
29  		}
30  		refcount_set(&hash->refs, 1);
31  		init_waitqueue_head(&hash->wait);
32  		ctx->hash_map = hash;
33  	}
34  	mutex_unlock(&ctx->uring_lock);
35  
36  	data.hash = hash;
37  	data.task = task;
38  	data.free_work = io_wq_free_work;
39  	data.do_work = io_wq_submit_work;
40  
41  	/* Do QD, or 4 * CPUS, whatever is smallest */
42  	concurrency = min(ctx->sq_entries, 4 * num_online_cpus());
43  
44  	return io_wq_create(concurrency, &data);
45  }
46  
47  void __io_uring_free(struct task_struct *tsk)
48  {
49  	struct io_uring_task *tctx = tsk->io_uring;
50  
51  	WARN_ON_ONCE(!xa_empty(&tctx->xa));
52  	WARN_ON_ONCE(tctx->io_wq);
53  	WARN_ON_ONCE(tctx->cached_refs);
54  
55  	percpu_counter_destroy(&tctx->inflight);
56  	kfree(tctx);
57  	tsk->io_uring = NULL;
58  }
59  
60  __cold int io_uring_alloc_task_context(struct task_struct *task,
61  				       struct io_ring_ctx *ctx)
62  {
63  	struct io_uring_task *tctx;
64  	int ret;
65  
66  	tctx = kzalloc(sizeof(*tctx), GFP_KERNEL);
67  	if (unlikely(!tctx))
68  		return -ENOMEM;
69  
70  	ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
71  	if (unlikely(ret)) {
72  		kfree(tctx);
73  		return ret;
74  	}
75  
76  	tctx->io_wq = io_init_wq_offload(ctx, task);
77  	if (IS_ERR(tctx->io_wq)) {
78  		ret = PTR_ERR(tctx->io_wq);
79  		percpu_counter_destroy(&tctx->inflight);
80  		kfree(tctx);
81  		return ret;
82  	}
83  
84  	xa_init(&tctx->xa);
85  	init_waitqueue_head(&tctx->wait);
86  	atomic_set(&tctx->in_cancel, 0);
87  	atomic_set(&tctx->inflight_tracked, 0);
88  	task->io_uring = tctx;
89  	init_llist_head(&tctx->task_list);
90  	init_task_work(&tctx->task_work, tctx_task_work);
91  	return 0;
92  }
93  
94  int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
95  {
96  	struct io_uring_task *tctx = current->io_uring;
97  	struct io_tctx_node *node;
98  	int ret;
99  
100  	if (unlikely(!tctx)) {
101  		ret = io_uring_alloc_task_context(current, ctx);
102  		if (unlikely(ret))
103  			return ret;
104  
105  		tctx = current->io_uring;
106  		if (ctx->iowq_limits_set) {
107  			unsigned int limits[2] = { ctx->iowq_limits[0],
108  						   ctx->iowq_limits[1], };
109  
110  			ret = io_wq_max_workers(tctx->io_wq, limits);
111  			if (ret)
112  				return ret;
113  		}
114  	}
115  	if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
116  		node = kmalloc(sizeof(*node), GFP_KERNEL);
117  		if (!node)
118  			return -ENOMEM;
119  		node->ctx = ctx;
120  		node->task = current;
121  
122  		ret = xa_err(xa_store(&tctx->xa, (unsigned long)ctx,
123  					node, GFP_KERNEL));
124  		if (ret) {
125  			kfree(node);
126  			return ret;
127  		}
128  
129  		mutex_lock(&ctx->uring_lock);
130  		list_add(&node->ctx_node, &ctx->tctx_list);
131  		mutex_unlock(&ctx->uring_lock);
132  	}
133  	return 0;
134  }
135  
136  int __io_uring_add_tctx_node_from_submit(struct io_ring_ctx *ctx)
137  {
138  	int ret;
139  
140  	if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
141  	    && ctx->submitter_task != current)
142  		return -EEXIST;
143  
144  	ret = __io_uring_add_tctx_node(ctx);
145  	if (ret)
146  		return ret;
147  
148  	current->io_uring->last = ctx;
149  	return 0;
150  }
151  
152  /*
153   * Remove this io_uring_file -> task mapping.
154   */
155  __cold void io_uring_del_tctx_node(unsigned long index)
156  {
157  	struct io_uring_task *tctx = current->io_uring;
158  	struct io_tctx_node *node;
159  
160  	if (!tctx)
161  		return;
162  	node = xa_erase(&tctx->xa, index);
163  	if (!node)
164  		return;
165  
166  	WARN_ON_ONCE(current != node->task);
167  	WARN_ON_ONCE(list_empty(&node->ctx_node));
168  
169  	mutex_lock(&node->ctx->uring_lock);
170  	list_del(&node->ctx_node);
171  	mutex_unlock(&node->ctx->uring_lock);
172  
173  	if (tctx->last == node->ctx)
174  		tctx->last = NULL;
175  	kfree(node);
176  }
177  
178  __cold void io_uring_clean_tctx(struct io_uring_task *tctx)
179  {
180  	struct io_wq *wq = tctx->io_wq;
181  	struct io_tctx_node *node;
182  	unsigned long index;
183  
184  	xa_for_each(&tctx->xa, index, node) {
185  		io_uring_del_tctx_node(index);
186  		cond_resched();
187  	}
188  	if (wq) {
189  		/*
190  		 * Must be after io_uring_del_tctx_node() (removes nodes under
191  		 * uring_lock) to avoid race with io_uring_try_cancel_iowq().
192  		 */
193  		io_wq_put_and_exit(wq);
194  		tctx->io_wq = NULL;
195  	}
196  }
197  
198  void io_uring_unreg_ringfd(void)
199  {
200  	struct io_uring_task *tctx = current->io_uring;
201  	int i;
202  
203  	for (i = 0; i < IO_RINGFD_REG_MAX; i++) {
204  		if (tctx->registered_rings[i]) {
205  			fput(tctx->registered_rings[i]);
206  			tctx->registered_rings[i] = NULL;
207  		}
208  	}
209  }
210  
211  static int io_ring_add_registered_fd(struct io_uring_task *tctx, int fd,
212  				     int start, int end)
213  {
214  	struct file *file;
215  	int offset;
216  
217  	for (offset = start; offset < end; offset++) {
218  		offset = array_index_nospec(offset, IO_RINGFD_REG_MAX);
219  		if (tctx->registered_rings[offset])
220  			continue;
221  
222  		file = fget(fd);
223  		if (!file) {
224  			return -EBADF;
225  		} else if (!io_is_uring_fops(file)) {
226  			fput(file);
227  			return -EOPNOTSUPP;
228  		}
229  		tctx->registered_rings[offset] = file;
230  		return offset;
231  	}
232  
233  	return -EBUSY;
234  }
235  
236  /*
237   * Register a ring fd to avoid fdget/fdput for each io_uring_enter()
238   * invocation. User passes in an array of struct io_uring_rsrc_update
239   * with ->data set to the ring_fd, and ->offset given for the desired
240   * index. If no index is desired, application may set ->offset == -1U
241   * and we'll find an available index. Returns number of entries
242   * successfully processed, or < 0 on error if none were processed.
243   */
244  int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg,
245  		       unsigned nr_args)
246  {
247  	struct io_uring_rsrc_update __user *arg = __arg;
248  	struct io_uring_rsrc_update reg;
249  	struct io_uring_task *tctx;
250  	int ret, i;
251  
252  	if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
253  		return -EINVAL;
254  
255  	mutex_unlock(&ctx->uring_lock);
256  	ret = __io_uring_add_tctx_node(ctx);
257  	mutex_lock(&ctx->uring_lock);
258  	if (ret)
259  		return ret;
260  
261  	tctx = current->io_uring;
262  	for (i = 0; i < nr_args; i++) {
263  		int start, end;
264  
265  		if (copy_from_user(&reg, &arg[i], sizeof(reg))) {
266  			ret = -EFAULT;
267  			break;
268  		}
269  
270  		if (reg.resv) {
271  			ret = -EINVAL;
272  			break;
273  		}
274  
275  		if (reg.offset == -1U) {
276  			start = 0;
277  			end = IO_RINGFD_REG_MAX;
278  		} else {
279  			if (reg.offset >= IO_RINGFD_REG_MAX) {
280  				ret = -EINVAL;
281  				break;
282  			}
283  			start = reg.offset;
284  			end = start + 1;
285  		}
286  
287  		ret = io_ring_add_registered_fd(tctx, reg.data, start, end);
288  		if (ret < 0)
289  			break;
290  
291  		reg.offset = ret;
292  		if (copy_to_user(&arg[i], &reg, sizeof(reg))) {
293  			fput(tctx->registered_rings[reg.offset]);
294  			tctx->registered_rings[reg.offset] = NULL;
295  			ret = -EFAULT;
296  			break;
297  		}
298  	}
299  
300  	return i ? i : ret;
301  }
302  
303  int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
304  			 unsigned nr_args)
305  {
306  	struct io_uring_rsrc_update __user *arg = __arg;
307  	struct io_uring_task *tctx = current->io_uring;
308  	struct io_uring_rsrc_update reg;
309  	int ret = 0, i;
310  
311  	if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
312  		return -EINVAL;
313  	if (!tctx)
314  		return 0;
315  
316  	for (i = 0; i < nr_args; i++) {
317  		if (copy_from_user(&reg, &arg[i], sizeof(reg))) {
318  			ret = -EFAULT;
319  			break;
320  		}
321  		if (reg.resv || reg.data || reg.offset >= IO_RINGFD_REG_MAX) {
322  			ret = -EINVAL;
323  			break;
324  		}
325  
326  		reg.offset = array_index_nospec(reg.offset, IO_RINGFD_REG_MAX);
327  		if (tctx->registered_rings[reg.offset]) {
328  			fput(tctx->registered_rings[reg.offset]);
329  			tctx->registered_rings[reg.offset] = NULL;
330  		}
331  	}
332  
333  	return i ? i : ret;
334  }
335