net/core/page_pool.c

   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 <net/xdp.h>
  15
  16 #include <linux/dma-direction.h>
  17 #include <linux/dma-mapping.h>
  18 #include <linux/page-flags.h>
  19 #include <linux/mm.h> /* for __put_page() */
  20
  21 #include <trace/events/page_pool.h>
  22
  23 #define DEFER_TIME (msecs_to_jiffies(1000))
  24 #define DEFER_WARN_INTERVAL (60 * HZ)
  25
  26 static int page_pool_init(struct page_pool *pool,
  27                           const struct page_pool_params *params)
  28 {
  29         unsigned int ring_qsize = 1024; /* Default */
  30
  31         memcpy(&pool->p, params, sizeof(pool->p));
  32
  33         /* Validate only known flags were used */
  34         if (pool->p.flags & ~(PP_FLAG_ALL))
  35                 return -EINVAL;
  36
  37         if (pool->p.pool_size)
  38                 ring_qsize = pool->p.pool_size;
  39
  40         /* Sanity limit mem that can be pinned down */
  41         if (ring_qsize > 32768)
  42                 return -E2BIG;
  43
  44         /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
  45          * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
  46          * which is the XDP_TX use-case.
  47          */
  48         if (pool->p.flags & PP_FLAG_DMA_MAP) {
  49                 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
  50                     (pool->p.dma_dir != DMA_BIDIRECTIONAL))
  51                         return -EINVAL;
  52         }
  53
  54         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
  55                 /* In order to request DMA-sync-for-device the page
  56                  * needs to be mapped
  57                  */
  58                 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
  59                         return -EINVAL;
  60
  61                 if (!pool->p.max_len)
  62                         return -EINVAL;
  63
  64                 /* pool->p.offset has to be set according to the address
  65                  * offset used by the DMA engine to start copying rx data
  66                  */
  67         }
  68
  69         if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
  70                 return -ENOMEM;
  71
  72         atomic_set(&pool->pages_state_release_cnt, 0);
  73
  74         /* Driver calling page_pool_create() also call page_pool_destroy() */
  75         refcount_set(&pool->user_cnt, 1);
  76
  77         if (pool->p.flags & PP_FLAG_DMA_MAP)
  78                 get_device(pool->p.dev);
  79
  80         return 0;
  81 }
  82
  83 struct page_pool *page_pool_create(const struct page_pool_params *params)
  84 {
  85         struct page_pool *pool;
  86         int err;
  87
  88         pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
  89         if (!pool)
  90                 return ERR_PTR(-ENOMEM);
  91
  92         err = page_pool_init(pool, params);
  93         if (err < 0) {
  94                 pr_warn("%s() gave up with errno %d\n", __func__, err);
  95                 kfree(pool);
  96                 return ERR_PTR(err);
  97         }
  98
  99         return pool;
 100 }
 101 EXPORT_SYMBOL(page_pool_create);
 102
 103 static void page_pool_return_page(struct page_pool *pool, struct page *page);
 104
 105 noinline
 106 static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
 107 {
 108         struct ptr_ring *r = &pool->ring;
 109         struct page *page;
 110         int pref_nid; /* preferred NUMA node */
 111
 112         /* Quicker fallback, avoid locks when ring is empty */
 113         if (__ptr_ring_empty(r))
 114                 return NULL;
 115
 116         /* Softirq guarantee CPU and thus NUMA node is stable. This,
 117          * assumes CPU refilling driver RX-ring will also run RX-NAPI.
 118          */
 119 #ifdef CONFIG_NUMA
 120         pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
 121 #else
 122         /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
 123         pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
 124 #endif
 125
 126         /* Slower-path: Get pages from locked ring queue */
 127         spin_lock(&r->consumer_lock);
 128
 129         /* Refill alloc array, but only if NUMA match */
 130         do {
 131                 page = __ptr_ring_consume(r);
 132                 if (unlikely(!page))
 133                         break;
 134
 135                 if (likely(page_to_nid(page) == pref_nid)) {
 136                         pool->alloc.cache[pool->alloc.count++] = page;
 137                 } else {
 138                         /* NUMA mismatch;
 139                          * (1) release 1 page to page-allocator and
 140                          * (2) break out to fallthrough to alloc_pages_node.
 141                          * This limit stress on page buddy alloactor.
 142                          */
 143                         page_pool_return_page(pool, page);
 144                         page = NULL;
 145                         break;
 146                 }
 147         } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
 148
 149         /* Return last page */
 150         if (likely(pool->alloc.count > 0))
 151                 page = pool->alloc.cache[--pool->alloc.count];
 152
 153         spin_unlock(&r->consumer_lock);
 154         return page;
 155 }
 156
 157 /* fast path */
 158 static struct page *__page_pool_get_cached(struct page_pool *pool)
 159 {
 160         struct page *page;
 161
 162         /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
 163         if (likely(pool->alloc.count)) {
 164                 /* Fast-path */
 165                 page = pool->alloc.cache[--pool->alloc.count];
 166         } else {
 167                 page = page_pool_refill_alloc_cache(pool);
 168         }
 169
 170         return page;
 171 }
 172
 173 static void page_pool_dma_sync_for_device(struct page_pool *pool,
 174                                           struct page *page,
 175                                           unsigned int dma_sync_size)
 176 {
 177         dma_sync_size = min(dma_sync_size, pool->p.max_len);
 178         dma_sync_single_range_for_device(pool->p.dev, page->dma_addr,
 179                                          pool->p.offset, dma_sync_size,
 180                                          pool->p.dma_dir);
 181 }
 182
 183 /* slow path */
 184 noinline
 185 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 186                                                  gfp_t _gfp)
 187 {
 188         struct page *page;
 189         gfp_t gfp = _gfp;
 190         dma_addr_t dma;
 191
 192         /* We could always set __GFP_COMP, and avoid this branch, as
 193          * prep_new_page() can handle order-0 with __GFP_COMP.
 194          */
 195         if (pool->p.order)
 196                 gfp |= __GFP_COMP;
 197
 198         /* FUTURE development:
 199          *
 200          * Current slow-path essentially falls back to single page
 201          * allocations, which doesn't improve performance.  This code
 202          * need bulk allocation support from the page allocator code.
 203          */
 204
 205         /* Cache was empty, do real allocation */
 206 #ifdef CONFIG_NUMA
 207         page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
 208 #else
 209         page = alloc_pages(gfp, pool->p.order);
 210 #endif
 211         if (!page)
 212                 return NULL;
 213
 214         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 215                 goto skip_dma_map;
 216
 217         /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
 218          * since dma_addr_t can be either 32 or 64 bits and does not always fit
 219          * into page private data (i.e 32bit cpu with 64bit DMA caps)
 220          * This mapping is kept for lifetime of page, until leaving pool.
 221          */
 222         dma = dma_map_page_attrs(pool->p.dev, page, 0,
 223                                  (PAGE_SIZE << pool->p.order),
 224                                  pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 225         if (dma_mapping_error(pool->p.dev, dma)) {
 226                 put_page(page);
 227                 return NULL;
 228         }
 229         page->dma_addr = dma;
 230
 231         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 232                 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
 233
 234 skip_dma_map:
 235         /* Track how many pages are held 'in-flight' */
 236         pool->pages_state_hold_cnt++;
 237
 238         trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
 239
 240         /* When page just alloc'ed is should/must have refcnt 1. */
 241         return page;
 242 }
 243
 244 /* For using page_pool replace: alloc_pages() API calls, but provide
 245  * synchronization guarantee for allocation side.
 246  */
 247 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 248 {
 249         struct page *page;
 250
 251         /* Fast-path: Get a page from cache */
 252         page = __page_pool_get_cached(pool);
 253         if (page)
 254                 return page;
 255
 256         /* Slow-path: cache empty, do real allocation */
 257         page = __page_pool_alloc_pages_slow(pool, gfp);
 258         return page;
 259 }
 260 EXPORT_SYMBOL(page_pool_alloc_pages);
 261
 262 /* Calculate distance between two u32 values, valid if distance is below 2^(31)
 263  *  https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
 264  */
 265 #define _distance(a, b) (s32)((a) - (b))
 266
 267 static s32 page_pool_inflight(struct page_pool *pool)
 268 {
 269         u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
 270         u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
 271         s32 inflight;
 272
 273         inflight = _distance(hold_cnt, release_cnt);
 274
 275         trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
 276         WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
 277
 278         return inflight;
 279 }
 280
 281 /* Disconnects a page (from a page_pool).  API users can have a need
 282  * to disconnect a page (from a page_pool), to allow it to be used as
 283  * a regular page (that will eventually be returned to the normal
 284  * page-allocator via put_page).
 285  */
 286 void page_pool_release_page(struct page_pool *pool, struct page *page)
 287 {
 288         dma_addr_t dma;
 289         int count;
 290
 291         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 292                 /* Always account for inflight pages, even if we didn't
 293                  * map them
 294                  */
 295                 goto skip_dma_unmap;
 296
 297         dma = page->dma_addr;
 298
 299         /* When page is unmapped, it cannot be returned our pool */
 300         dma_unmap_page_attrs(pool->p.dev, dma,
 301                              PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 302                              DMA_ATTR_SKIP_CPU_SYNC);
 303         page->dma_addr = 0;
 304 skip_dma_unmap:
 305         /* This may be the last page returned, releasing the pool, so
 306          * it is not safe to reference pool afterwards.
 307          */
 308         count = atomic_inc_return(&pool->pages_state_release_cnt);
 309         trace_page_pool_state_release(pool, page, count);
 310 }
 311 EXPORT_SYMBOL(page_pool_release_page);
 312
 313 /* Return a page to the page allocator, cleaning up our state */
 314 static void page_pool_return_page(struct page_pool *pool, struct page *page)
 315 {
 316         page_pool_release_page(pool, page);
 317
 318         put_page(page);
 319         /* An optimization would be to call __free_pages(page, pool->p.order)
 320          * knowing page is not part of page-cache (thus avoiding a
 321          * __page_cache_release() call).
 322          */
 323 }
 324
 325 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
 326 {
 327         int ret;
 328         /* BH protection not needed if current is serving softirq */
 329         if (in_serving_softirq())
 330                 ret = ptr_ring_produce(&pool->ring, page);
 331         else
 332                 ret = ptr_ring_produce_bh(&pool->ring, page);
 333
 334         return (ret == 0) ? true : false;
 335 }
 336
 337 /* Only allow direct recycling in special circumstances, into the
 338  * alloc side cache.  E.g. during RX-NAPI processing for XDP_DROP use-case.
 339  *
 340  * Caller must provide appropriate safe context.
 341  */
 342 static bool page_pool_recycle_in_cache(struct page *page,
 343                                        struct page_pool *pool)
 344 {
 345         if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
 346                 return false;
 347
 348         /* Caller MUST have verified/know (page_ref_count(page) == 1) */
 349         pool->alloc.cache[pool->alloc.count++] = page;
 350         return true;
 351 }
 352
 353 /* If the page refcnt == 1, this will try to recycle the page.
 354  * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
 355  * the configured size min(dma_sync_size, pool->max_len).
 356  * If the page refcnt != 1, then the page will be returned to memory
 357  * subsystem.
 358  */
 359 static __always_inline struct page *
 360 __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          * page is NOT reusable when allocated when system is under
 370          * some pressure. (page_is_pfmemalloc)
 371          */
 372         if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
 373                 /* Read barrier done in page_ref_count / READ_ONCE */
 374
 375                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 376                         page_pool_dma_sync_for_device(pool, page,
 377                                                       dma_sync_size);
 378
 379                 if (allow_direct && in_serving_softirq() &&
 380                     page_pool_recycle_in_cache(page, pool))
 381                         return NULL;
 382
 383                 /* Page found as candidate for recycling */
 384                 return page;
 385         }
 386         /* Fallback/non-XDP mode: API user have elevated refcnt.
 387          *
 388          * Many drivers split up the page into fragments, and some
 389          * want to keep doing this to save memory and do refcnt based
 390          * recycling. Support this use case too, to ease drivers
 391          * switching between XDP/non-XDP.
 392          *
 393          * In-case page_pool maintains the DMA mapping, API user must
 394          * call page_pool_put_page once.  In this elevated refcnt
 395          * case, the DMA is unmapped/released, as driver is likely
 396          * doing refcnt based recycle tricks, meaning another process
 397          * will be invoking put_page.
 398          */
 399         /* Do not replace this with page_pool_return_page() */
 400         page_pool_release_page(pool, page);
 401         put_page(page);
 402
 403         return NULL;
 404 }
 405
 406 void page_pool_put_page(struct page_pool *pool, struct page *page,
 407                         unsigned int dma_sync_size, bool allow_direct)
 408 {
 409         page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
 410         if (page && !page_pool_recycle_in_ring(pool, page)) {
 411                 /* Cache full, fallback to free pages */
 412                 page_pool_return_page(pool, page);
 413         }
 414 }
 415 EXPORT_SYMBOL(page_pool_put_page);
 416
 417 /* Caller must not use data area after call, as this function overwrites it */
 418 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 419                              int count)
 420 {
 421         int i, bulk_len = 0;
 422
 423         for (i = 0; i < count; i++) {
 424                 struct page *page = virt_to_head_page(data[i]);
 425
 426                 page = __page_pool_put_page(pool, page, -1, false);
 427                 /* Approved for bulk recycling in ptr_ring cache */
 428                 if (page)
 429                         data[bulk_len++] = page;
 430         }
 431
 432         if (unlikely(!bulk_len))
 433                 return;
 434
 435         /* Bulk producer into ptr_ring page_pool cache */
 436         page_pool_ring_lock(pool);
 437         for (i = 0; i < bulk_len; i++) {
 438                 if (__ptr_ring_produce(&pool->ring, data[i]))
 439                         break; /* ring full */
 440         }
 441         page_pool_ring_unlock(pool);
 442
 443         /* Hopefully all pages was return into ptr_ring */
 444         if (likely(i == bulk_len))
 445                 return;
 446
 447         /* ptr_ring cache full, free remaining pages outside producer lock
 448          * since put_page() with refcnt == 1 can be an expensive operation
 449          */
 450         for (; i < bulk_len; i++)
 451                 page_pool_return_page(pool, data[i]);
 452 }
 453 EXPORT_SYMBOL(page_pool_put_page_bulk);
 454
 455 static void page_pool_empty_ring(struct page_pool *pool)
 456 {
 457         struct page *page;
 458
 459         /* Empty recycle ring */
 460         while ((page = ptr_ring_consume_bh(&pool->ring))) {
 461                 /* Verify the refcnt invariant of cached pages */
 462                 if (!(page_ref_count(page) == 1))
 463                         pr_crit("%s() page_pool refcnt %d violation\n",
 464                                 __func__, page_ref_count(page));
 465
 466                 page_pool_return_page(pool, page);
 467         }
 468 }
 469
 470 static void page_pool_free(struct page_pool *pool)
 471 {
 472         if (pool->disconnect)
 473                 pool->disconnect(pool);
 474
 475         ptr_ring_cleanup(&pool->ring, NULL);
 476
 477         if (pool->p.flags & PP_FLAG_DMA_MAP)
 478                 put_device(pool->p.dev);
 479
 480         kfree(pool);
 481 }
 482
 483 static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
 484 {
 485         struct page *page;
 486
 487         if (pool->destroy_cnt)
 488                 return;
 489
 490         /* Empty alloc cache, assume caller made sure this is
 491          * no-longer in use, and page_pool_alloc_pages() cannot be
 492          * call concurrently.
 493          */
 494         while (pool->alloc.count) {
 495                 page = pool->alloc.cache[--pool->alloc.count];
 496                 page_pool_return_page(pool, page);
 497         }
 498 }
 499
 500 static void page_pool_scrub(struct page_pool *pool)
 501 {
 502         page_pool_empty_alloc_cache_once(pool);
 503         pool->destroy_cnt++;
 504
 505         /* No more consumers should exist, but producers could still
 506          * be in-flight.
 507          */
 508         page_pool_empty_ring(pool);
 509 }
 510
 511 static int page_pool_release(struct page_pool *pool)
 512 {
 513         int inflight;
 514
 515         page_pool_scrub(pool);
 516         inflight = page_pool_inflight(pool);
 517         if (!inflight)
 518                 page_pool_free(pool);
 519
 520         return inflight;
 521 }
 522
 523 static void page_pool_release_retry(struct work_struct *wq)
 524 {
 525         struct delayed_work *dwq = to_delayed_work(wq);
 526         struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
 527         int inflight;
 528
 529         inflight = page_pool_release(pool);
 530         if (!inflight)
 531                 return;
 532
 533         /* Periodic warning */
 534         if (time_after_eq(jiffies, pool->defer_warn)) {
 535                 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
 536
 537                 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
 538                         __func__, inflight, sec);
 539                 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
 540         }
 541
 542         /* Still not ready to be disconnected, retry later */
 543         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 544 }
 545
 546 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
 547 {
 548         refcount_inc(&pool->user_cnt);
 549         pool->disconnect = disconnect;
 550 }
 551
 552 void page_pool_destroy(struct page_pool *pool)
 553 {
 554         if (!pool)
 555                 return;
 556
 557         if (!page_pool_put(pool))
 558                 return;
 559
 560         if (!page_pool_release(pool))
 561                 return;
 562
 563         pool->defer_start = jiffies;
 564         pool->defer_warn  = jiffies + DEFER_WARN_INTERVAL;
 565
 566         INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
 567         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 568 }
 569 EXPORT_SYMBOL(page_pool_destroy);
 570
 571 /* Caller must provide appropriate safe context, e.g. NAPI. */
 572 void page_pool_update_nid(struct page_pool *pool, int new_nid)
 573 {
 574         struct page *page;
 575
 576         trace_page_pool_update_nid(pool, new_nid);
 577         pool->p.nid = new_nid;
 578
 579         /* Flush pool alloc cache, as refill will check NUMA node */
 580         while (pool->alloc.count) {
 581                 page = pool->alloc.cache[--pool->alloc.count];
 582                 page_pool_return_page(pool, page);
 583         }
 584 }
 585 EXPORT_SYMBOL(page_pool_update_nid);