1 /* SPDX-License-Identifier: GPL-2.0 2 * 3 * page_pool.c 4 * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com> 5 * Copyright (C) 2016 Red Hat, Inc. 6 */ 7 8 #include <linux/types.h> 9 #include <linux/kernel.h> 10 #include <linux/slab.h> 11 #include <linux/device.h> 12 13 #include <net/page_pool.h> 14 #include <linux/dma-direction.h> 15 #include <linux/dma-mapping.h> 16 #include <linux/page-flags.h> 17 #include <linux/mm.h> /* for __put_page() */ 18 19 #include <trace/events/page_pool.h> 20 21 #define DEFER_TIME (msecs_to_jiffies(1000)) 22 #define DEFER_WARN_INTERVAL (60 * HZ) 23 24 static int page_pool_init(struct page_pool *pool, 25 const struct page_pool_params *params) 26 { 27 unsigned int ring_qsize = 1024; /* Default */ 28 29 memcpy(&pool->p, params, sizeof(pool->p)); 30 31 /* Validate only known flags were used */ 32 if (pool->p.flags & ~(PP_FLAG_ALL)) 33 return -EINVAL; 34 35 if (pool->p.pool_size) 36 ring_qsize = pool->p.pool_size; 37 38 /* Sanity limit mem that can be pinned down */ 39 if (ring_qsize > 32768) 40 return -E2BIG; 41 42 /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL. 43 * DMA_BIDIRECTIONAL is for allowing page used for DMA sending, 44 * which is the XDP_TX use-case. 45 */ 46 if ((pool->p.dma_dir != DMA_FROM_DEVICE) && 47 (pool->p.dma_dir != DMA_BIDIRECTIONAL)) 48 return -EINVAL; 49 50 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) { 51 /* In order to request DMA-sync-for-device the page 52 * needs to be mapped 53 */ 54 if (!(pool->p.flags & PP_FLAG_DMA_MAP)) 55 return -EINVAL; 56 57 if (!pool->p.max_len) 58 return -EINVAL; 59 60 /* pool->p.offset has to be set according to the address 61 * offset used by the DMA engine to start copying rx data 62 */ 63 } 64 65 if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0) 66 return -ENOMEM; 67 68 atomic_set(&pool->pages_state_release_cnt, 0); 69 70 /* Driver calling page_pool_create() also call page_pool_destroy() */ 71 refcount_set(&pool->user_cnt, 1); 72 73 if (pool->p.flags & PP_FLAG_DMA_MAP) 74 get_device(pool->p.dev); 75 76 return 0; 77 } 78 79 struct page_pool *page_pool_create(const struct page_pool_params *params) 80 { 81 struct page_pool *pool; 82 int err; 83 84 pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid); 85 if (!pool) 86 return ERR_PTR(-ENOMEM); 87 88 err = page_pool_init(pool, params); 89 if (err < 0) { 90 pr_warn("%s() gave up with errno %d\n", __func__, err); 91 kfree(pool); 92 return ERR_PTR(err); 93 } 94 95 return pool; 96 } 97 EXPORT_SYMBOL(page_pool_create); 98 99 static void __page_pool_return_page(struct page_pool *pool, struct page *page); 100 101 noinline 102 static struct page *page_pool_refill_alloc_cache(struct page_pool *pool) 103 { 104 struct ptr_ring *r = &pool->ring; 105 struct page *page; 106 int pref_nid; /* preferred NUMA node */ 107 108 /* Quicker fallback, avoid locks when ring is empty */ 109 if (__ptr_ring_empty(r)) 110 return NULL; 111 112 /* Softirq guarantee CPU and thus NUMA node is stable. This, 113 * assumes CPU refilling driver RX-ring will also run RX-NAPI. 114 */ 115 #ifdef CONFIG_NUMA 116 pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid; 117 #else 118 /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */ 119 pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */ 120 #endif 121 122 /* Slower-path: Get pages from locked ring queue */ 123 spin_lock(&r->consumer_lock); 124 125 /* Refill alloc array, but only if NUMA match */ 126 do { 127 page = __ptr_ring_consume(r); 128 if (unlikely(!page)) 129 break; 130 131 if (likely(page_to_nid(page) == pref_nid)) { 132 pool->alloc.cache[pool->alloc.count++] = page; 133 } else { 134 /* NUMA mismatch; 135 * (1) release 1 page to page-allocator and 136 * (2) break out to fallthrough to alloc_pages_node. 137 * This limit stress on page buddy alloactor. 138 */ 139 __page_pool_return_page(pool, page); 140 page = NULL; 141 break; 142 } 143 } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL); 144 145 /* Return last page */ 146 if (likely(pool->alloc.count > 0)) 147 page = pool->alloc.cache[--pool->alloc.count]; 148 149 spin_unlock(&r->consumer_lock); 150 return page; 151 } 152 153 /* fast path */ 154 static struct page *__page_pool_get_cached(struct page_pool *pool) 155 { 156 struct page *page; 157 158 /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */ 159 if (likely(pool->alloc.count)) { 160 /* Fast-path */ 161 page = pool->alloc.cache[--pool->alloc.count]; 162 } else { 163 page = page_pool_refill_alloc_cache(pool); 164 } 165 166 return page; 167 } 168 169 static void page_pool_dma_sync_for_device(struct page_pool *pool, 170 struct page *page, 171 unsigned int dma_sync_size) 172 { 173 dma_sync_size = min(dma_sync_size, pool->p.max_len); 174 dma_sync_single_range_for_device(pool->p.dev, page->dma_addr, 175 pool->p.offset, dma_sync_size, 176 pool->p.dma_dir); 177 } 178 179 /* slow path */ 180 noinline 181 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool, 182 gfp_t _gfp) 183 { 184 struct page *page; 185 gfp_t gfp = _gfp; 186 dma_addr_t dma; 187 188 /* We could always set __GFP_COMP, and avoid this branch, as 189 * prep_new_page() can handle order-0 with __GFP_COMP. 190 */ 191 if (pool->p.order) 192 gfp |= __GFP_COMP; 193 194 /* FUTURE development: 195 * 196 * Current slow-path essentially falls back to single page 197 * allocations, which doesn't improve performance. This code 198 * need bulk allocation support from the page allocator code. 199 */ 200 201 /* Cache was empty, do real allocation */ 202 #ifdef CONFIG_NUMA 203 page = alloc_pages_node(pool->p.nid, gfp, pool->p.order); 204 #else 205 page = alloc_pages(gfp, pool->p.order); 206 #endif 207 if (!page) 208 return NULL; 209 210 if (!(pool->p.flags & PP_FLAG_DMA_MAP)) 211 goto skip_dma_map; 212 213 /* Setup DMA mapping: use 'struct page' area for storing DMA-addr 214 * since dma_addr_t can be either 32 or 64 bits and does not always fit 215 * into page private data (i.e 32bit cpu with 64bit DMA caps) 216 * This mapping is kept for lifetime of page, until leaving pool. 217 */ 218 dma = dma_map_page_attrs(pool->p.dev, page, 0, 219 (PAGE_SIZE << pool->p.order), 220 pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); 221 if (dma_mapping_error(pool->p.dev, dma)) { 222 put_page(page); 223 return NULL; 224 } 225 page->dma_addr = dma; 226 227 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) 228 page_pool_dma_sync_for_device(pool, page, pool->p.max_len); 229 230 skip_dma_map: 231 /* Track how many pages are held 'in-flight' */ 232 pool->pages_state_hold_cnt++; 233 234 trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt); 235 236 /* When page just alloc'ed is should/must have refcnt 1. */ 237 return page; 238 } 239 240 /* For using page_pool replace: alloc_pages() API calls, but provide 241 * synchronization guarantee for allocation side. 242 */ 243 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp) 244 { 245 struct page *page; 246 247 /* Fast-path: Get a page from cache */ 248 page = __page_pool_get_cached(pool); 249 if (page) 250 return page; 251 252 /* Slow-path: cache empty, do real allocation */ 253 page = __page_pool_alloc_pages_slow(pool, gfp); 254 return page; 255 } 256 EXPORT_SYMBOL(page_pool_alloc_pages); 257 258 /* Calculate distance between two u32 values, valid if distance is below 2^(31) 259 * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution 260 */ 261 #define _distance(a, b) (s32)((a) - (b)) 262 263 static s32 page_pool_inflight(struct page_pool *pool) 264 { 265 u32 release_cnt = atomic_read(&pool->pages_state_release_cnt); 266 u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt); 267 s32 inflight; 268 269 inflight = _distance(hold_cnt, release_cnt); 270 271 trace_page_pool_release(pool, inflight, hold_cnt, release_cnt); 272 WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight); 273 274 return inflight; 275 } 276 277 /* Cleanup page_pool state from page */ 278 static void __page_pool_clean_page(struct page_pool *pool, 279 struct page *page) 280 { 281 dma_addr_t dma; 282 int count; 283 284 if (!(pool->p.flags & PP_FLAG_DMA_MAP)) 285 goto skip_dma_unmap; 286 287 dma = page->dma_addr; 288 /* DMA unmap */ 289 dma_unmap_page_attrs(pool->p.dev, dma, 290 PAGE_SIZE << pool->p.order, pool->p.dma_dir, 291 DMA_ATTR_SKIP_CPU_SYNC); 292 page->dma_addr = 0; 293 skip_dma_unmap: 294 /* This may be the last page returned, releasing the pool, so 295 * it is not safe to reference pool afterwards. 296 */ 297 count = atomic_inc_return(&pool->pages_state_release_cnt); 298 trace_page_pool_state_release(pool, page, count); 299 } 300 301 /* unmap the page and clean our state */ 302 void page_pool_unmap_page(struct page_pool *pool, struct page *page) 303 { 304 /* When page is unmapped, this implies page will not be 305 * returned to page_pool. 306 */ 307 __page_pool_clean_page(pool, page); 308 } 309 EXPORT_SYMBOL(page_pool_unmap_page); 310 311 /* Return a page to the page allocator, cleaning up our state */ 312 static void __page_pool_return_page(struct page_pool *pool, struct page *page) 313 { 314 __page_pool_clean_page(pool, page); 315 316 put_page(page); 317 /* An optimization would be to call __free_pages(page, pool->p.order) 318 * knowing page is not part of page-cache (thus avoiding a 319 * __page_cache_release() call). 320 */ 321 } 322 323 static bool __page_pool_recycle_into_ring(struct page_pool *pool, 324 struct page *page) 325 { 326 int ret; 327 /* BH protection not needed if current is serving softirq */ 328 if (in_serving_softirq()) 329 ret = ptr_ring_produce(&pool->ring, page); 330 else 331 ret = ptr_ring_produce_bh(&pool->ring, page); 332 333 return (ret == 0) ? true : false; 334 } 335 336 /* Only allow direct recycling in special circumstances, into the 337 * alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case. 338 * 339 * Caller must provide appropriate safe context. 340 */ 341 static bool __page_pool_recycle_direct(struct page *page, 342 struct page_pool *pool) 343 { 344 if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) 345 return false; 346 347 /* Caller MUST have verified/know (page_ref_count(page) == 1) */ 348 pool->alloc.cache[pool->alloc.count++] = page; 349 return true; 350 } 351 352 /* page is NOT reusable when: 353 * 1) allocated when system is under some pressure. (page_is_pfmemalloc) 354 */ 355 static bool pool_page_reusable(struct page_pool *pool, struct page *page) 356 { 357 return !page_is_pfmemalloc(page); 358 } 359 360 void __page_pool_put_page(struct page_pool *pool, struct page *page, 361 unsigned int dma_sync_size, bool allow_direct) 362 { 363 /* This allocator is optimized for the XDP mode that uses 364 * one-frame-per-page, but have fallbacks that act like the 365 * regular page allocator APIs. 366 * 367 * refcnt == 1 means page_pool owns page, and can recycle it. 368 */ 369 if (likely(page_ref_count(page) == 1 && 370 pool_page_reusable(pool, page))) { 371 /* Read barrier done in page_ref_count / READ_ONCE */ 372 373 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) 374 page_pool_dma_sync_for_device(pool, page, 375 dma_sync_size); 376 377 if (allow_direct && in_serving_softirq()) 378 if (__page_pool_recycle_direct(page, pool)) 379 return; 380 381 if (!__page_pool_recycle_into_ring(pool, page)) { 382 /* Cache full, fallback to free pages */ 383 __page_pool_return_page(pool, page); 384 } 385 return; 386 } 387 /* Fallback/non-XDP mode: API user have elevated refcnt. 388 * 389 * Many drivers split up the page into fragments, and some 390 * want to keep doing this to save memory and do refcnt based 391 * recycling. Support this use case too, to ease drivers 392 * switching between XDP/non-XDP. 393 * 394 * In-case page_pool maintains the DMA mapping, API user must 395 * call page_pool_put_page once. In this elevated refcnt 396 * case, the DMA is unmapped/released, as driver is likely 397 * doing refcnt based recycle tricks, meaning another process 398 * will be invoking put_page. 399 */ 400 __page_pool_clean_page(pool, page); 401 put_page(page); 402 } 403 EXPORT_SYMBOL(__page_pool_put_page); 404 405 static void __page_pool_empty_ring(struct page_pool *pool) 406 { 407 struct page *page; 408 409 /* Empty recycle ring */ 410 while ((page = ptr_ring_consume_bh(&pool->ring))) { 411 /* Verify the refcnt invariant of cached pages */ 412 if (!(page_ref_count(page) == 1)) 413 pr_crit("%s() page_pool refcnt %d violation\n", 414 __func__, page_ref_count(page)); 415 416 __page_pool_return_page(pool, page); 417 } 418 } 419 420 static void page_pool_free(struct page_pool *pool) 421 { 422 if (pool->disconnect) 423 pool->disconnect(pool); 424 425 ptr_ring_cleanup(&pool->ring, NULL); 426 427 if (pool->p.flags & PP_FLAG_DMA_MAP) 428 put_device(pool->p.dev); 429 430 kfree(pool); 431 } 432 433 static void page_pool_empty_alloc_cache_once(struct page_pool *pool) 434 { 435 struct page *page; 436 437 if (pool->destroy_cnt) 438 return; 439 440 /* Empty alloc cache, assume caller made sure this is 441 * no-longer in use, and page_pool_alloc_pages() cannot be 442 * call concurrently. 443 */ 444 while (pool->alloc.count) { 445 page = pool->alloc.cache[--pool->alloc.count]; 446 __page_pool_return_page(pool, page); 447 } 448 } 449 450 static void page_pool_scrub(struct page_pool *pool) 451 { 452 page_pool_empty_alloc_cache_once(pool); 453 pool->destroy_cnt++; 454 455 /* No more consumers should exist, but producers could still 456 * be in-flight. 457 */ 458 __page_pool_empty_ring(pool); 459 } 460 461 static int page_pool_release(struct page_pool *pool) 462 { 463 int inflight; 464 465 page_pool_scrub(pool); 466 inflight = page_pool_inflight(pool); 467 if (!inflight) 468 page_pool_free(pool); 469 470 return inflight; 471 } 472 473 static void page_pool_release_retry(struct work_struct *wq) 474 { 475 struct delayed_work *dwq = to_delayed_work(wq); 476 struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw); 477 int inflight; 478 479 inflight = page_pool_release(pool); 480 if (!inflight) 481 return; 482 483 /* Periodic warning */ 484 if (time_after_eq(jiffies, pool->defer_warn)) { 485 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ; 486 487 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n", 488 __func__, inflight, sec); 489 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL; 490 } 491 492 /* Still not ready to be disconnected, retry later */ 493 schedule_delayed_work(&pool->release_dw, DEFER_TIME); 494 } 495 496 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *)) 497 { 498 refcount_inc(&pool->user_cnt); 499 pool->disconnect = disconnect; 500 } 501 502 void page_pool_destroy(struct page_pool *pool) 503 { 504 if (!pool) 505 return; 506 507 if (!page_pool_put(pool)) 508 return; 509 510 if (!page_pool_release(pool)) 511 return; 512 513 pool->defer_start = jiffies; 514 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL; 515 516 INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry); 517 schedule_delayed_work(&pool->release_dw, DEFER_TIME); 518 } 519 EXPORT_SYMBOL(page_pool_destroy); 520 521 /* Caller must provide appropriate safe context, e.g. NAPI. */ 522 void page_pool_update_nid(struct page_pool *pool, int new_nid) 523 { 524 struct page *page; 525 526 trace_page_pool_update_nid(pool, new_nid); 527 pool->p.nid = new_nid; 528 529 /* Flush pool alloc cache, as refill will check NUMA node */ 530 while (pool->alloc.count) { 531 page = pool->alloc.cache[--pool->alloc.count]; 532 __page_pool_return_page(pool, page); 533 } 534 } 535 EXPORT_SYMBOL(page_pool_update_nid); 536