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_addr_t dma_addr = page_pool_get_dma_addr(page);
 178
 179         dma_sync_size = min(dma_sync_size, pool->p.max_len);
 180         dma_sync_single_range_for_device(pool->p.dev, dma_addr,
 181                                          pool->p.offset, dma_sync_size,
 182                                          pool->p.dma_dir);
 183 }
 184
 185 static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
 186 {
 187         dma_addr_t dma;
 188
 189         /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
 190          * since dma_addr_t can be either 32 or 64 bits and does not always fit
 191          * into page private data (i.e 32bit cpu with 64bit DMA caps)
 192          * This mapping is kept for lifetime of page, until leaving pool.
 193          */
 194         dma = dma_map_page_attrs(pool->p.dev, page, 0,
 195                                  (PAGE_SIZE << pool->p.order),
 196                                  pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 197         if (dma_mapping_error(pool->p.dev, dma))
 198                 return false;
 199
 200         page_pool_set_dma_addr(page, dma);
 201
 202         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 203                 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
 204
 205         return true;
 206 }
 207
 208 static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
 209                                                  gfp_t gfp)
 210 {
 211         struct page *page;
 212
 213         gfp |= __GFP_COMP;
 214         page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
 215         if (unlikely(!page))
 216                 return NULL;
 217
 218         if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
 219             unlikely(!page_pool_dma_map(pool, page))) {
 220                 put_page(page);
 221                 return NULL;
 222         }
 223
 224         /* Track how many pages are held 'in-flight' */
 225         pool->pages_state_hold_cnt++;
 226         trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
 227         return page;
 228 }
 229
 230 /* slow path */
 231 noinline
 232 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 233                                                  gfp_t gfp)
 234 {
 235         const int bulk = PP_ALLOC_CACHE_REFILL;
 236         unsigned int pp_flags = pool->p.flags;
 237         unsigned int pp_order = pool->p.order;
 238         struct page *page;
 239         int i, nr_pages;
 240
 241         /* Don't support bulk alloc for high-order pages */
 242         if (unlikely(pp_order))
 243                 return __page_pool_alloc_page_order(pool, gfp);
 244
 245         /* Unnecessary as alloc cache is empty, but guarantees zero count */
 246         if (unlikely(pool->alloc.count > 0))
 247                 return pool->alloc.cache[--pool->alloc.count];
 248
 249         /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
 250         memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
 251
 252         nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
 253         if (unlikely(!nr_pages))
 254                 return NULL;
 255
 256         /* Pages have been filled into alloc.cache array, but count is zero and
 257          * page element have not been (possibly) DMA mapped.
 258          */
 259         for (i = 0; i < nr_pages; i++) {
 260                 page = pool->alloc.cache[i];
 261                 if ((pp_flags & PP_FLAG_DMA_MAP) &&
 262                     unlikely(!page_pool_dma_map(pool, page))) {
 263                         put_page(page);
 264                         continue;
 265                 }
 266                 pool->alloc.cache[pool->alloc.count++] = page;
 267                 /* Track how many pages are held 'in-flight' */
 268                 pool->pages_state_hold_cnt++;
 269                 trace_page_pool_state_hold(pool, page,
 270                                            pool->pages_state_hold_cnt);
 271         }
 272
 273         /* Return last page */
 274         if (likely(pool->alloc.count > 0))
 275                 page = pool->alloc.cache[--pool->alloc.count];
 276         else
 277                 page = NULL;
 278
 279         /* When page just alloc'ed is should/must have refcnt 1. */
 280         return page;
 281 }
 282
 283 /* For using page_pool replace: alloc_pages() API calls, but provide
 284  * synchronization guarantee for allocation side.
 285  */
 286 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 287 {
 288         struct page *page;
 289
 290         /* Fast-path: Get a page from cache */
 291         page = __page_pool_get_cached(pool);
 292         if (page)
 293                 return page;
 294
 295         /* Slow-path: cache empty, do real allocation */
 296         page = __page_pool_alloc_pages_slow(pool, gfp);
 297         return page;
 298 }
 299 EXPORT_SYMBOL(page_pool_alloc_pages);
 300
 301 /* Calculate distance between two u32 values, valid if distance is below 2^(31)
 302  *  https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
 303  */
 304 #define _distance(a, b) (s32)((a) - (b))
 305
 306 static s32 page_pool_inflight(struct page_pool *pool)
 307 {
 308         u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
 309         u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
 310         s32 inflight;
 311
 312         inflight = _distance(hold_cnt, release_cnt);
 313
 314         trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
 315         WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
 316
 317         return inflight;
 318 }
 319
 320 /* Disconnects a page (from a page_pool).  API users can have a need
 321  * to disconnect a page (from a page_pool), to allow it to be used as
 322  * a regular page (that will eventually be returned to the normal
 323  * page-allocator via put_page).
 324  */
 325 void page_pool_release_page(struct page_pool *pool, struct page *page)
 326 {
 327         dma_addr_t dma;
 328         int count;
 329
 330         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 331                 /* Always account for inflight pages, even if we didn't
 332                  * map them
 333                  */
 334                 goto skip_dma_unmap;
 335
 336         dma = page_pool_get_dma_addr(page);
 337
 338         /* When page is unmapped, it cannot be returned to our pool */
 339         dma_unmap_page_attrs(pool->p.dev, dma,
 340                              PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 341                              DMA_ATTR_SKIP_CPU_SYNC);
 342         page_pool_set_dma_addr(page, 0);
 343 skip_dma_unmap:
 344         /* This may be the last page returned, releasing the pool, so
 345          * it is not safe to reference pool afterwards.
 346          */
 347         count = atomic_inc_return(&pool->pages_state_release_cnt);
 348         trace_page_pool_state_release(pool, page, count);
 349 }
 350 EXPORT_SYMBOL(page_pool_release_page);
 351
 352 /* Return a page to the page allocator, cleaning up our state */
 353 static void page_pool_return_page(struct page_pool *pool, struct page *page)
 354 {
 355         page_pool_release_page(pool, page);
 356
 357         put_page(page);
 358         /* An optimization would be to call __free_pages(page, pool->p.order)
 359          * knowing page is not part of page-cache (thus avoiding a
 360          * __page_cache_release() call).
 361          */
 362 }
 363
 364 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
 365 {
 366         int ret;
 367         /* BH protection not needed if current is serving softirq */
 368         if (in_serving_softirq())
 369                 ret = ptr_ring_produce(&pool->ring, page);
 370         else
 371                 ret = ptr_ring_produce_bh(&pool->ring, page);
 372
 373         return (ret == 0) ? true : false;
 374 }
 375
 376 /* Only allow direct recycling in special circumstances, into the
 377  * alloc side cache.  E.g. during RX-NAPI processing for XDP_DROP use-case.
 378  *
 379  * Caller must provide appropriate safe context.
 380  */
 381 static bool page_pool_recycle_in_cache(struct page *page,
 382                                        struct page_pool *pool)
 383 {
 384         if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
 385                 return false;
 386
 387         /* Caller MUST have verified/know (page_ref_count(page) == 1) */
 388         pool->alloc.cache[pool->alloc.count++] = page;
 389         return true;
 390 }
 391
 392 /* If the page refcnt == 1, this will try to recycle the page.
 393  * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
 394  * the configured size min(dma_sync_size, pool->max_len).
 395  * If the page refcnt != 1, then the page will be returned to memory
 396  * subsystem.
 397  */
 398 static __always_inline struct page *
 399 __page_pool_put_page(struct page_pool *pool, struct page *page,
 400                      unsigned int dma_sync_size, bool allow_direct)
 401 {
 402         /* This allocator is optimized for the XDP mode that uses
 403          * one-frame-per-page, but have fallbacks that act like the
 404          * regular page allocator APIs.
 405          *
 406          * refcnt == 1 means page_pool owns page, and can recycle it.
 407          *
 408          * page is NOT reusable when allocated when system is under
 409          * some pressure. (page_is_pfmemalloc)
 410          */
 411         if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
 412                 /* Read barrier done in page_ref_count / READ_ONCE */
 413
 414                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 415                         page_pool_dma_sync_for_device(pool, page,
 416                                                       dma_sync_size);
 417
 418                 if (allow_direct && in_serving_softirq() &&
 419                     page_pool_recycle_in_cache(page, pool))
 420                         return NULL;
 421
 422                 /* Page found as candidate for recycling */
 423                 return page;
 424         }
 425         /* Fallback/non-XDP mode: API user have elevated refcnt.
 426          *
 427          * Many drivers split up the page into fragments, and some
 428          * want to keep doing this to save memory and do refcnt based
 429          * recycling. Support this use case too, to ease drivers
 430          * switching between XDP/non-XDP.
 431          *
 432          * In-case page_pool maintains the DMA mapping, API user must
 433          * call page_pool_put_page once.  In this elevated refcnt
 434          * case, the DMA is unmapped/released, as driver is likely
 435          * doing refcnt based recycle tricks, meaning another process
 436          * will be invoking put_page.
 437          */
 438         /* Do not replace this with page_pool_return_page() */
 439         page_pool_release_page(pool, page);
 440         put_page(page);
 441
 442         return NULL;
 443 }
 444
 445 void page_pool_put_page(struct page_pool *pool, struct page *page,
 446                         unsigned int dma_sync_size, bool allow_direct)
 447 {
 448         page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
 449         if (page && !page_pool_recycle_in_ring(pool, page)) {
 450                 /* Cache full, fallback to free pages */
 451                 page_pool_return_page(pool, page);
 452         }
 453 }
 454 EXPORT_SYMBOL(page_pool_put_page);
 455
 456 /* Caller must not use data area after call, as this function overwrites it */
 457 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 458                              int count)
 459 {
 460         int i, bulk_len = 0;
 461
 462         for (i = 0; i < count; i++) {
 463                 struct page *page = virt_to_head_page(data[i]);
 464
 465                 page = __page_pool_put_page(pool, page, -1, false);
 466                 /* Approved for bulk recycling in ptr_ring cache */
 467                 if (page)
 468                         data[bulk_len++] = page;
 469         }
 470
 471         if (unlikely(!bulk_len))
 472                 return;
 473
 474         /* Bulk producer into ptr_ring page_pool cache */
 475         page_pool_ring_lock(pool);
 476         for (i = 0; i < bulk_len; i++) {
 477                 if (__ptr_ring_produce(&pool->ring, data[i]))
 478                         break; /* ring full */
 479         }
 480         page_pool_ring_unlock(pool);
 481
 482         /* Hopefully all pages was return into ptr_ring */
 483         if (likely(i == bulk_len))
 484                 return;
 485
 486         /* ptr_ring cache full, free remaining pages outside producer lock
 487          * since put_page() with refcnt == 1 can be an expensive operation
 488          */
 489         for (; i < bulk_len; i++)
 490                 page_pool_return_page(pool, data[i]);
 491 }
 492 EXPORT_SYMBOL(page_pool_put_page_bulk);
 493
 494 static void page_pool_empty_ring(struct page_pool *pool)
 495 {
 496         struct page *page;
 497
 498         /* Empty recycle ring */
 499         while ((page = ptr_ring_consume_bh(&pool->ring))) {
 500                 /* Verify the refcnt invariant of cached pages */
 501                 if (!(page_ref_count(page) == 1))
 502                         pr_crit("%s() page_pool refcnt %d violation\n",
 503                                 __func__, page_ref_count(page));
 504
 505                 page_pool_return_page(pool, page);
 506         }
 507 }
 508
 509 static void page_pool_free(struct page_pool *pool)
 510 {
 511         if (pool->disconnect)
 512                 pool->disconnect(pool);
 513
 514         ptr_ring_cleanup(&pool->ring, NULL);
 515
 516         if (pool->p.flags & PP_FLAG_DMA_MAP)
 517                 put_device(pool->p.dev);
 518
 519         kfree(pool);
 520 }
 521
 522 static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
 523 {
 524         struct page *page;
 525
 526         if (pool->destroy_cnt)
 527                 return;
 528
 529         /* Empty alloc cache, assume caller made sure this is
 530          * no-longer in use, and page_pool_alloc_pages() cannot be
 531          * call concurrently.
 532          */
 533         while (pool->alloc.count) {
 534                 page = pool->alloc.cache[--pool->alloc.count];
 535                 page_pool_return_page(pool, page);
 536         }
 537 }
 538
 539 static void page_pool_scrub(struct page_pool *pool)
 540 {
 541         page_pool_empty_alloc_cache_once(pool);
 542         pool->destroy_cnt++;
 543
 544         /* No more consumers should exist, but producers could still
 545          * be in-flight.
 546          */
 547         page_pool_empty_ring(pool);
 548 }
 549
 550 static int page_pool_release(struct page_pool *pool)
 551 {
 552         int inflight;
 553
 554         page_pool_scrub(pool);
 555         inflight = page_pool_inflight(pool);
 556         if (!inflight)
 557                 page_pool_free(pool);
 558
 559         return inflight;
 560 }
 561
 562 static void page_pool_release_retry(struct work_struct *wq)
 563 {
 564         struct delayed_work *dwq = to_delayed_work(wq);
 565         struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
 566         int inflight;
 567
 568         inflight = page_pool_release(pool);
 569         if (!inflight)
 570                 return;
 571
 572         /* Periodic warning */
 573         if (time_after_eq(jiffies, pool->defer_warn)) {
 574                 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
 575
 576                 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
 577                         __func__, inflight, sec);
 578                 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
 579         }
 580
 581         /* Still not ready to be disconnected, retry later */
 582         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 583 }
 584
 585 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
 586 {
 587         refcount_inc(&pool->user_cnt);
 588         pool->disconnect = disconnect;
 589 }
 590
 591 void page_pool_destroy(struct page_pool *pool)
 592 {
 593         if (!pool)
 594                 return;
 595
 596         if (!page_pool_put(pool))
 597                 return;
 598
 599         if (!page_pool_release(pool))
 600                 return;
 601
 602         pool->defer_start = jiffies;
 603         pool->defer_warn  = jiffies + DEFER_WARN_INTERVAL;
 604
 605         INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
 606         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 607 }
 608 EXPORT_SYMBOL(page_pool_destroy);
 609
 610 /* Caller must provide appropriate safe context, e.g. NAPI. */
 611 void page_pool_update_nid(struct page_pool *pool, int new_nid)
 612 {
 613         struct page *page;
 614
 615         trace_page_pool_update_nid(pool, new_nid);
 616         pool->p.nid = new_nid;
 617
 618         /* Flush pool alloc cache, as refill will check NUMA node */
 619         while (pool->alloc.count) {
 620                 page = pool->alloc.cache[--pool->alloc.count];
 621                 page_pool_return_page(pool, page);
 622         }
 623 }
 624 EXPORT_SYMBOL(page_pool_update_nid);