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/helpers.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 #include <linux/poison.h>
  21 #include <linux/ethtool.h>
  22 #include <linux/netdevice.h>
  23
  24 #include <trace/events/page_pool.h>
  25
  26 #include "page_pool_priv.h"
  27
  28 #define DEFER_TIME (msecs_to_jiffies(1000))
  29 #define DEFER_WARN_INTERVAL (60 * HZ)
  30
  31 #define BIAS_MAX        (LONG_MAX >> 1)
  32
  33 #ifdef CONFIG_PAGE_POOL_STATS
  34 static DEFINE_PER_CPU(struct page_pool_recycle_stats, pp_system_recycle_stats);
  35
  36 /* alloc_stat_inc is intended to be used in softirq context */
  37 #define alloc_stat_inc(pool, __stat)    (pool->alloc_stats.__stat++)
  38 /* recycle_stat_inc is safe to use when preemption is possible. */
  39 #define recycle_stat_inc(pool, __stat)                                                  \
  40         do {                                                                            \
  41                 struct page_pool_recycle_stats __percpu *s = pool->recycle_stats;       \
  42                 this_cpu_inc(s->__stat);                                                \
  43         } while (0)
  44
  45 #define recycle_stat_add(pool, __stat, val)                                             \
  46         do {                                                                            \
  47                 struct page_pool_recycle_stats __percpu *s = pool->recycle_stats;       \
  48                 this_cpu_add(s->__stat, val);                                           \
  49         } while (0)
  50
  51 static const char pp_stats[][ETH_GSTRING_LEN] = {
  52         "rx_pp_alloc_fast",
  53         "rx_pp_alloc_slow",
  54         "rx_pp_alloc_slow_ho",
  55         "rx_pp_alloc_empty",
  56         "rx_pp_alloc_refill",
  57         "rx_pp_alloc_waive",
  58         "rx_pp_recycle_cached",
  59         "rx_pp_recycle_cache_full",
  60         "rx_pp_recycle_ring",
  61         "rx_pp_recycle_ring_full",
  62         "rx_pp_recycle_released_ref",
  63 };
  64
  65 /**
  66  * page_pool_get_stats() - fetch page pool stats
  67  * @pool:       pool from which page was allocated
  68  * @stats:      struct page_pool_stats to fill in
  69  *
  70  * Retrieve statistics about the page_pool. This API is only available
  71  * if the kernel has been configured with ``CONFIG_PAGE_POOL_STATS=y``.
  72  * A pointer to a caller allocated struct page_pool_stats structure
  73  * is passed to this API which is filled in. The caller can then report
  74  * those stats to the user (perhaps via ethtool, debugfs, etc.).
  75  */
  76 bool page_pool_get_stats(const struct page_pool *pool,
  77                          struct page_pool_stats *stats)
  78 {
  79         int cpu = 0;
  80
  81         if (!stats)
  82                 return false;
  83
  84         /* The caller is responsible to initialize stats. */
  85         stats->alloc_stats.fast += pool->alloc_stats.fast;
  86         stats->alloc_stats.slow += pool->alloc_stats.slow;
  87         stats->alloc_stats.slow_high_order += pool->alloc_stats.slow_high_order;
  88         stats->alloc_stats.empty += pool->alloc_stats.empty;
  89         stats->alloc_stats.refill += pool->alloc_stats.refill;
  90         stats->alloc_stats.waive += pool->alloc_stats.waive;
  91
  92         for_each_possible_cpu(cpu) {
  93                 const struct page_pool_recycle_stats *pcpu =
  94                         per_cpu_ptr(pool->recycle_stats, cpu);
  95
  96                 stats->recycle_stats.cached += pcpu->cached;
  97                 stats->recycle_stats.cache_full += pcpu->cache_full;
  98                 stats->recycle_stats.ring += pcpu->ring;
  99                 stats->recycle_stats.ring_full += pcpu->ring_full;
 100                 stats->recycle_stats.released_refcnt += pcpu->released_refcnt;
 101         }
 102
 103         return true;
 104 }
 105 EXPORT_SYMBOL(page_pool_get_stats);
 106
 107 u8 *page_pool_ethtool_stats_get_strings(u8 *data)
 108 {
 109         int i;
 110
 111         for (i = 0; i < ARRAY_SIZE(pp_stats); i++) {
 112                 memcpy(data, pp_stats[i], ETH_GSTRING_LEN);
 113                 data += ETH_GSTRING_LEN;
 114         }
 115
 116         return data;
 117 }
 118 EXPORT_SYMBOL(page_pool_ethtool_stats_get_strings);
 119
 120 int page_pool_ethtool_stats_get_count(void)
 121 {
 122         return ARRAY_SIZE(pp_stats);
 123 }
 124 EXPORT_SYMBOL(page_pool_ethtool_stats_get_count);
 125
 126 u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
 127 {
 128         struct page_pool_stats *pool_stats = stats;
 129
 130         *data++ = pool_stats->alloc_stats.fast;
 131         *data++ = pool_stats->alloc_stats.slow;
 132         *data++ = pool_stats->alloc_stats.slow_high_order;
 133         *data++ = pool_stats->alloc_stats.empty;
 134         *data++ = pool_stats->alloc_stats.refill;
 135         *data++ = pool_stats->alloc_stats.waive;
 136         *data++ = pool_stats->recycle_stats.cached;
 137         *data++ = pool_stats->recycle_stats.cache_full;
 138         *data++ = pool_stats->recycle_stats.ring;
 139         *data++ = pool_stats->recycle_stats.ring_full;
 140         *data++ = pool_stats->recycle_stats.released_refcnt;
 141
 142         return data;
 143 }
 144 EXPORT_SYMBOL(page_pool_ethtool_stats_get);
 145
 146 #else
 147 #define alloc_stat_inc(pool, __stat)
 148 #define recycle_stat_inc(pool, __stat)
 149 #define recycle_stat_add(pool, __stat, val)
 150 #endif
 151
 152 static bool page_pool_producer_lock(struct page_pool *pool)
 153         __acquires(&pool->ring.producer_lock)
 154 {
 155         bool in_softirq = in_softirq();
 156
 157         if (in_softirq)
 158                 spin_lock(&pool->ring.producer_lock);
 159         else
 160                 spin_lock_bh(&pool->ring.producer_lock);
 161
 162         return in_softirq;
 163 }
 164
 165 static void page_pool_producer_unlock(struct page_pool *pool,
 166                                       bool in_softirq)
 167         __releases(&pool->ring.producer_lock)
 168 {
 169         if (in_softirq)
 170                 spin_unlock(&pool->ring.producer_lock);
 171         else
 172                 spin_unlock_bh(&pool->ring.producer_lock);
 173 }
 174
 175 static int page_pool_init(struct page_pool *pool,
 176                           const struct page_pool_params *params,
 177                           int cpuid)
 178 {
 179         unsigned int ring_qsize = 1024; /* Default */
 180
 181         memcpy(&pool->p, &params->fast, sizeof(pool->p));
 182         memcpy(&pool->slow, &params->slow, sizeof(pool->slow));
 183
 184         pool->cpuid = cpuid;
 185
 186         /* Validate only known flags were used */
 187         if (pool->p.flags & ~(PP_FLAG_ALL))
 188                 return -EINVAL;
 189
 190         if (pool->p.pool_size)
 191                 ring_qsize = pool->p.pool_size;
 192
 193         /* Sanity limit mem that can be pinned down */
 194         if (ring_qsize > 32768)
 195                 return -E2BIG;
 196
 197         /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
 198          * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
 199          * which is the XDP_TX use-case.
 200          */
 201         if (pool->p.flags & PP_FLAG_DMA_MAP) {
 202                 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
 203                     (pool->p.dma_dir != DMA_BIDIRECTIONAL))
 204                         return -EINVAL;
 205         }
 206
 207         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
 208                 /* In order to request DMA-sync-for-device the page
 209                  * needs to be mapped
 210                  */
 211                 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 212                         return -EINVAL;
 213
 214                 if (!pool->p.max_len)
 215                         return -EINVAL;
 216
 217                 /* pool->p.offset has to be set according to the address
 218                  * offset used by the DMA engine to start copying rx data
 219                  */
 220         }
 221
 222         pool->has_init_callback = !!pool->slow.init_callback;
 223
 224 #ifdef CONFIG_PAGE_POOL_STATS
 225         if (!(pool->p.flags & PP_FLAG_SYSTEM_POOL)) {
 226                 pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats);
 227                 if (!pool->recycle_stats)
 228                         return -ENOMEM;
 229         } else {
 230                 /* For system page pool instance we use a singular stats object
 231                  * instead of allocating a separate percpu variable for each
 232                  * (also percpu) page pool instance.
 233                  */
 234                 pool->recycle_stats = &pp_system_recycle_stats;
 235         }
 236 #endif
 237
 238         if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0) {
 239 #ifdef CONFIG_PAGE_POOL_STATS
 240                 if (!(pool->p.flags & PP_FLAG_SYSTEM_POOL))
 241                         free_percpu(pool->recycle_stats);
 242 #endif
 243                 return -ENOMEM;
 244         }
 245
 246         atomic_set(&pool->pages_state_release_cnt, 0);
 247
 248         /* Driver calling page_pool_create() also call page_pool_destroy() */
 249         refcount_set(&pool->user_cnt, 1);
 250
 251         if (pool->p.flags & PP_FLAG_DMA_MAP)
 252                 get_device(pool->p.dev);
 253
 254         return 0;
 255 }
 256
 257 static void page_pool_uninit(struct page_pool *pool)
 258 {
 259         ptr_ring_cleanup(&pool->ring, NULL);
 260
 261         if (pool->p.flags & PP_FLAG_DMA_MAP)
 262                 put_device(pool->p.dev);
 263
 264 #ifdef CONFIG_PAGE_POOL_STATS
 265         if (!(pool->p.flags & PP_FLAG_SYSTEM_POOL))
 266                 free_percpu(pool->recycle_stats);
 267 #endif
 268 }
 269
 270 /**
 271  * page_pool_create_percpu() - create a page pool for a given cpu.
 272  * @params: parameters, see struct page_pool_params
 273  * @cpuid: cpu identifier
 274  */
 275 struct page_pool *
 276 page_pool_create_percpu(const struct page_pool_params *params, int cpuid)
 277 {
 278         struct page_pool *pool;
 279         int err;
 280
 281         pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
 282         if (!pool)
 283                 return ERR_PTR(-ENOMEM);
 284
 285         err = page_pool_init(pool, params, cpuid);
 286         if (err < 0)
 287                 goto err_free;
 288
 289         err = page_pool_list(pool);
 290         if (err)
 291                 goto err_uninit;
 292
 293         return pool;
 294
 295 err_uninit:
 296         page_pool_uninit(pool);
 297 err_free:
 298         pr_warn("%s() gave up with errno %d\n", __func__, err);
 299         kfree(pool);
 300         return ERR_PTR(err);
 301 }
 302 EXPORT_SYMBOL(page_pool_create_percpu);
 303
 304 /**
 305  * page_pool_create() - create a page pool
 306  * @params: parameters, see struct page_pool_params
 307  */
 308 struct page_pool *page_pool_create(const struct page_pool_params *params)
 309 {
 310         return page_pool_create_percpu(params, -1);
 311 }
 312 EXPORT_SYMBOL(page_pool_create);
 313
 314 static void page_pool_return_page(struct page_pool *pool, struct page *page);
 315
 316 noinline
 317 static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
 318 {
 319         struct ptr_ring *r = &pool->ring;
 320         struct page *page;
 321         int pref_nid; /* preferred NUMA node */
 322
 323         /* Quicker fallback, avoid locks when ring is empty */
 324         if (__ptr_ring_empty(r)) {
 325                 alloc_stat_inc(pool, empty);
 326                 return NULL;
 327         }
 328
 329         /* Softirq guarantee CPU and thus NUMA node is stable. This,
 330          * assumes CPU refilling driver RX-ring will also run RX-NAPI.
 331          */
 332 #ifdef CONFIG_NUMA
 333         pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
 334 #else
 335         /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
 336         pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
 337 #endif
 338
 339         /* Refill alloc array, but only if NUMA match */
 340         do {
 341                 page = __ptr_ring_consume(r);
 342                 if (unlikely(!page))
 343                         break;
 344
 345                 if (likely(page_to_nid(page) == pref_nid)) {
 346                         pool->alloc.cache[pool->alloc.count++] = page;
 347                 } else {
 348                         /* NUMA mismatch;
 349                          * (1) release 1 page to page-allocator and
 350                          * (2) break out to fallthrough to alloc_pages_node.
 351                          * This limit stress on page buddy alloactor.
 352                          */
 353                         page_pool_return_page(pool, page);
 354                         alloc_stat_inc(pool, waive);
 355                         page = NULL;
 356                         break;
 357                 }
 358         } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
 359
 360         /* Return last page */
 361         if (likely(pool->alloc.count > 0)) {
 362                 page = pool->alloc.cache[--pool->alloc.count];
 363                 alloc_stat_inc(pool, refill);
 364         }
 365
 366         return page;
 367 }
 368
 369 /* fast path */
 370 static struct page *__page_pool_get_cached(struct page_pool *pool)
 371 {
 372         struct page *page;
 373
 374         /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
 375         if (likely(pool->alloc.count)) {
 376                 /* Fast-path */
 377                 page = pool->alloc.cache[--pool->alloc.count];
 378                 alloc_stat_inc(pool, fast);
 379         } else {
 380                 page = page_pool_refill_alloc_cache(pool);
 381         }
 382
 383         return page;
 384 }
 385
 386 static void page_pool_dma_sync_for_device(struct page_pool *pool,
 387                                           struct page *page,
 388                                           unsigned int dma_sync_size)
 389 {
 390         dma_addr_t dma_addr = page_pool_get_dma_addr(page);
 391
 392         dma_sync_size = min(dma_sync_size, pool->p.max_len);
 393         dma_sync_single_range_for_device(pool->p.dev, dma_addr,
 394                                          pool->p.offset, dma_sync_size,
 395                                          pool->p.dma_dir);
 396 }
 397
 398 static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
 399 {
 400         dma_addr_t dma;
 401
 402         /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
 403          * since dma_addr_t can be either 32 or 64 bits and does not always fit
 404          * into page private data (i.e 32bit cpu with 64bit DMA caps)
 405          * This mapping is kept for lifetime of page, until leaving pool.
 406          */
 407         dma = dma_map_page_attrs(pool->p.dev, page, 0,
 408                                  (PAGE_SIZE << pool->p.order),
 409                                  pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC |
 410                                                   DMA_ATTR_WEAK_ORDERING);
 411         if (dma_mapping_error(pool->p.dev, dma))
 412                 return false;
 413
 414         if (page_pool_set_dma_addr(page, dma))
 415                 goto unmap_failed;
 416
 417         if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 418                 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
 419
 420         return true;
 421
 422 unmap_failed:
 423         WARN_ON_ONCE("unexpected DMA address, please report to netdev@");
 424         dma_unmap_page_attrs(pool->p.dev, dma,
 425                              PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 426                              DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
 427         return false;
 428 }
 429
 430 static void page_pool_set_pp_info(struct page_pool *pool,
 431                                   struct page *page)
 432 {
 433         page->pp = pool;
 434         page->pp_magic |= PP_SIGNATURE;
 435
 436         /* Ensuring all pages have been split into one fragment initially:
 437          * page_pool_set_pp_info() is only called once for every page when it
 438          * is allocated from the page allocator and page_pool_fragment_page()
 439          * is dirtying the same cache line as the page->pp_magic above, so
 440          * the overhead is negligible.
 441          */
 442         page_pool_fragment_page(page, 1);
 443         if (pool->has_init_callback)
 444                 pool->slow.init_callback(page, pool->slow.init_arg);
 445 }
 446
 447 static void page_pool_clear_pp_info(struct page *page)
 448 {
 449         page->pp_magic = 0;
 450         page->pp = NULL;
 451 }
 452
 453 static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
 454                                                  gfp_t gfp)
 455 {
 456         struct page *page;
 457
 458         gfp |= __GFP_COMP;
 459         page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
 460         if (unlikely(!page))
 461                 return NULL;
 462
 463         if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
 464             unlikely(!page_pool_dma_map(pool, page))) {
 465                 put_page(page);
 466                 return NULL;
 467         }
 468
 469         alloc_stat_inc(pool, slow_high_order);
 470         page_pool_set_pp_info(pool, page);
 471
 472         /* Track how many pages are held 'in-flight' */
 473         pool->pages_state_hold_cnt++;
 474         trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
 475         return page;
 476 }
 477
 478 /* slow path */
 479 noinline
 480 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 481                                                  gfp_t gfp)
 482 {
 483         const int bulk = PP_ALLOC_CACHE_REFILL;
 484         unsigned int pp_flags = pool->p.flags;
 485         unsigned int pp_order = pool->p.order;
 486         struct page *page;
 487         int i, nr_pages;
 488
 489         /* Don't support bulk alloc for high-order pages */
 490         if (unlikely(pp_order))
 491                 return __page_pool_alloc_page_order(pool, gfp);
 492
 493         /* Unnecessary as alloc cache is empty, but guarantees zero count */
 494         if (unlikely(pool->alloc.count > 0))
 495                 return pool->alloc.cache[--pool->alloc.count];
 496
 497         /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
 498         memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
 499
 500         nr_pages = alloc_pages_bulk_array_node(gfp, pool->p.nid, bulk,
 501                                                pool->alloc.cache);
 502         if (unlikely(!nr_pages))
 503                 return NULL;
 504
 505         /* Pages have been filled into alloc.cache array, but count is zero and
 506          * page element have not been (possibly) DMA mapped.
 507          */
 508         for (i = 0; i < nr_pages; i++) {
 509                 page = pool->alloc.cache[i];
 510                 if ((pp_flags & PP_FLAG_DMA_MAP) &&
 511                     unlikely(!page_pool_dma_map(pool, page))) {
 512                         put_page(page);
 513                         continue;
 514                 }
 515
 516                 page_pool_set_pp_info(pool, page);
 517                 pool->alloc.cache[pool->alloc.count++] = page;
 518                 /* Track how many pages are held 'in-flight' */
 519                 pool->pages_state_hold_cnt++;
 520                 trace_page_pool_state_hold(pool, page,
 521                                            pool->pages_state_hold_cnt);
 522         }
 523
 524         /* Return last page */
 525         if (likely(pool->alloc.count > 0)) {
 526                 page = pool->alloc.cache[--pool->alloc.count];
 527                 alloc_stat_inc(pool, slow);
 528         } else {
 529                 page = NULL;
 530         }
 531
 532         /* When page just alloc'ed is should/must have refcnt 1. */
 533         return page;
 534 }
 535
 536 /* For using page_pool replace: alloc_pages() API calls, but provide
 537  * synchronization guarantee for allocation side.
 538  */
 539 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 540 {
 541         struct page *page;
 542
 543         /* Fast-path: Get a page from cache */
 544         page = __page_pool_get_cached(pool);
 545         if (page)
 546                 return page;
 547
 548         /* Slow-path: cache empty, do real allocation */
 549         page = __page_pool_alloc_pages_slow(pool, gfp);
 550         return page;
 551 }
 552 EXPORT_SYMBOL(page_pool_alloc_pages);
 553
 554 /* Calculate distance between two u32 values, valid if distance is below 2^(31)
 555  *  https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
 556  */
 557 #define _distance(a, b) (s32)((a) - (b))
 558
 559 s32 page_pool_inflight(const struct page_pool *pool, bool strict)
 560 {
 561         u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
 562         u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
 563         s32 inflight;
 564
 565         inflight = _distance(hold_cnt, release_cnt);
 566
 567         if (strict) {
 568                 trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
 569                 WARN(inflight < 0, "Negative(%d) inflight packet-pages",
 570                      inflight);
 571         } else {
 572                 inflight = max(0, inflight);
 573         }
 574
 575         return inflight;
 576 }
 577
 578 static __always_inline
 579 void __page_pool_release_page_dma(struct page_pool *pool, struct page *page)
 580 {
 581         dma_addr_t dma;
 582
 583         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 584                 /* Always account for inflight pages, even if we didn't
 585                  * map them
 586                  */
 587                 return;
 588
 589         dma = page_pool_get_dma_addr(page);
 590
 591         /* When page is unmapped, it cannot be returned to our pool */
 592         dma_unmap_page_attrs(pool->p.dev, dma,
 593                              PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 594                              DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
 595         page_pool_set_dma_addr(page, 0);
 596 }
 597
 598 /* Disconnects a page (from a page_pool).  API users can have a need
 599  * to disconnect a page (from a page_pool), to allow it to be used as
 600  * a regular page (that will eventually be returned to the normal
 601  * page-allocator via put_page).
 602  */
 603 void page_pool_return_page(struct page_pool *pool, struct page *page)
 604 {
 605         int count;
 606
 607         __page_pool_release_page_dma(pool, page);
 608
 609         page_pool_clear_pp_info(page);
 610
 611         /* This may be the last page returned, releasing the pool, so
 612          * it is not safe to reference pool afterwards.
 613          */
 614         count = atomic_inc_return_relaxed(&pool->pages_state_release_cnt);
 615         trace_page_pool_state_release(pool, page, count);
 616
 617         put_page(page);
 618         /* An optimization would be to call __free_pages(page, pool->p.order)
 619          * knowing page is not part of page-cache (thus avoiding a
 620          * __page_cache_release() call).
 621          */
 622 }
 623
 624 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
 625 {
 626         int ret;
 627         /* BH protection not needed if current is softirq */
 628         if (in_softirq())
 629                 ret = ptr_ring_produce(&pool->ring, page);
 630         else
 631                 ret = ptr_ring_produce_bh(&pool->ring, page);
 632
 633         if (!ret) {
 634                 recycle_stat_inc(pool, ring);
 635                 return true;
 636         }
 637
 638         return false;
 639 }
 640
 641 /* Only allow direct recycling in special circumstances, into the
 642  * alloc side cache.  E.g. during RX-NAPI processing for XDP_DROP use-case.
 643  *
 644  * Caller must provide appropriate safe context.
 645  */
 646 static bool page_pool_recycle_in_cache(struct page *page,
 647                                        struct page_pool *pool)
 648 {
 649         if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) {
 650                 recycle_stat_inc(pool, cache_full);
 651                 return false;
 652         }
 653
 654         /* Caller MUST have verified/know (page_ref_count(page) == 1) */
 655         pool->alloc.cache[pool->alloc.count++] = page;
 656         recycle_stat_inc(pool, cached);
 657         return true;
 658 }
 659
 660 static bool __page_pool_page_can_be_recycled(const struct page *page)
 661 {
 662         return page_ref_count(page) == 1 && !page_is_pfmemalloc(page);
 663 }
 664
 665 /* If the page refcnt == 1, this will try to recycle the page.
 666  * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
 667  * the configured size min(dma_sync_size, pool->max_len).
 668  * If the page refcnt != 1, then the page will be returned to memory
 669  * subsystem.
 670  */
 671 static __always_inline struct page *
 672 __page_pool_put_page(struct page_pool *pool, struct page *page,
 673                      unsigned int dma_sync_size, bool allow_direct)
 674 {
 675         lockdep_assert_no_hardirq();
 676
 677         /* This allocator is optimized for the XDP mode that uses
 678          * one-frame-per-page, but have fallbacks that act like the
 679          * regular page allocator APIs.
 680          *
 681          * refcnt == 1 means page_pool owns page, and can recycle it.
 682          *
 683          * page is NOT reusable when allocated when system is under
 684          * some pressure. (page_is_pfmemalloc)
 685          */
 686         if (likely(__page_pool_page_can_be_recycled(page))) {
 687                 /* Read barrier done in page_ref_count / READ_ONCE */
 688
 689                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 690                         page_pool_dma_sync_for_device(pool, page,
 691                                                       dma_sync_size);
 692
 693                 if (allow_direct && in_softirq() &&
 694                     page_pool_recycle_in_cache(page, pool))
 695                         return NULL;
 696
 697                 /* Page found as candidate for recycling */
 698                 return page;
 699         }
 700         /* Fallback/non-XDP mode: API user have elevated refcnt.
 701          *
 702          * Many drivers split up the page into fragments, and some
 703          * want to keep doing this to save memory and do refcnt based
 704          * recycling. Support this use case too, to ease drivers
 705          * switching between XDP/non-XDP.
 706          *
 707          * In-case page_pool maintains the DMA mapping, API user must
 708          * call page_pool_put_page once.  In this elevated refcnt
 709          * case, the DMA is unmapped/released, as driver is likely
 710          * doing refcnt based recycle tricks, meaning another process
 711          * will be invoking put_page.
 712          */
 713         recycle_stat_inc(pool, released_refcnt);
 714         page_pool_return_page(pool, page);
 715
 716         return NULL;
 717 }
 718
 719 void page_pool_put_unrefed_page(struct page_pool *pool, struct page *page,
 720                                 unsigned int dma_sync_size, bool allow_direct)
 721 {
 722         page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
 723         if (page && !page_pool_recycle_in_ring(pool, page)) {
 724                 /* Cache full, fallback to free pages */
 725                 recycle_stat_inc(pool, ring_full);
 726                 page_pool_return_page(pool, page);
 727         }
 728 }
 729 EXPORT_SYMBOL(page_pool_put_unrefed_page);
 730
 731 /**
 732  * page_pool_put_page_bulk() - release references on multiple pages
 733  * @pool:       pool from which pages were allocated
 734  * @data:       array holding page pointers
 735  * @count:      number of pages in @data
 736  *
 737  * Tries to refill a number of pages into the ptr_ring cache holding ptr_ring
 738  * producer lock. If the ptr_ring is full, page_pool_put_page_bulk()
 739  * will release leftover pages to the page allocator.
 740  * page_pool_put_page_bulk() is suitable to be run inside the driver NAPI tx
 741  * completion loop for the XDP_REDIRECT use case.
 742  *
 743  * Please note the caller must not use data area after running
 744  * page_pool_put_page_bulk(), as this function overwrites it.
 745  */
 746 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 747                              int count)
 748 {
 749         int i, bulk_len = 0;
 750         bool in_softirq;
 751
 752         for (i = 0; i < count; i++) {
 753                 struct page *page = virt_to_head_page(data[i]);
 754
 755                 /* It is not the last user for the page frag case */
 756                 if (!page_pool_is_last_ref(page))
 757                         continue;
 758
 759                 page = __page_pool_put_page(pool, page, -1, false);
 760                 /* Approved for bulk recycling in ptr_ring cache */
 761                 if (page)
 762                         data[bulk_len++] = page;
 763         }
 764
 765         if (unlikely(!bulk_len))
 766                 return;
 767
 768         /* Bulk producer into ptr_ring page_pool cache */
 769         in_softirq = page_pool_producer_lock(pool);
 770         for (i = 0; i < bulk_len; i++) {
 771                 if (__ptr_ring_produce(&pool->ring, data[i])) {
 772                         /* ring full */
 773                         recycle_stat_inc(pool, ring_full);
 774                         break;
 775                 }
 776         }
 777         recycle_stat_add(pool, ring, i);
 778         page_pool_producer_unlock(pool, in_softirq);
 779
 780         /* Hopefully all pages was return into ptr_ring */
 781         if (likely(i == bulk_len))
 782                 return;
 783
 784         /* ptr_ring cache full, free remaining pages outside producer lock
 785          * since put_page() with refcnt == 1 can be an expensive operation
 786          */
 787         for (; i < bulk_len; i++)
 788                 page_pool_return_page(pool, data[i]);
 789 }
 790 EXPORT_SYMBOL(page_pool_put_page_bulk);
 791
 792 static struct page *page_pool_drain_frag(struct page_pool *pool,
 793                                          struct page *page)
 794 {
 795         long drain_count = BIAS_MAX - pool->frag_users;
 796
 797         /* Some user is still using the page frag */
 798         if (likely(page_pool_unref_page(page, drain_count)))
 799                 return NULL;
 800
 801         if (__page_pool_page_can_be_recycled(page)) {
 802                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 803                         page_pool_dma_sync_for_device(pool, page, -1);
 804
 805                 return page;
 806         }
 807
 808         page_pool_return_page(pool, page);
 809         return NULL;
 810 }
 811
 812 static void page_pool_free_frag(struct page_pool *pool)
 813 {
 814         long drain_count = BIAS_MAX - pool->frag_users;
 815         struct page *page = pool->frag_page;
 816
 817         pool->frag_page = NULL;
 818
 819         if (!page || page_pool_unref_page(page, drain_count))
 820                 return;
 821
 822         page_pool_return_page(pool, page);
 823 }
 824
 825 struct page *page_pool_alloc_frag(struct page_pool *pool,
 826                                   unsigned int *offset,
 827                                   unsigned int size, gfp_t gfp)
 828 {
 829         unsigned int max_size = PAGE_SIZE << pool->p.order;
 830         struct page *page = pool->frag_page;
 831
 832         if (WARN_ON(size > max_size))
 833                 return NULL;
 834
 835         size = ALIGN(size, dma_get_cache_alignment());
 836         *offset = pool->frag_offset;
 837
 838         if (page && *offset + size > max_size) {
 839                 page = page_pool_drain_frag(pool, page);
 840                 if (page) {
 841                         alloc_stat_inc(pool, fast);
 842                         goto frag_reset;
 843                 }
 844         }
 845
 846         if (!page) {
 847                 page = page_pool_alloc_pages(pool, gfp);
 848                 if (unlikely(!page)) {
 849                         pool->frag_page = NULL;
 850                         return NULL;
 851                 }
 852
 853                 pool->frag_page = page;
 854
 855 frag_reset:
 856                 pool->frag_users = 1;
 857                 *offset = 0;
 858                 pool->frag_offset = size;
 859                 page_pool_fragment_page(page, BIAS_MAX);
 860                 return page;
 861         }
 862
 863         pool->frag_users++;
 864         pool->frag_offset = *offset + size;
 865         alloc_stat_inc(pool, fast);
 866         return page;
 867 }
 868 EXPORT_SYMBOL(page_pool_alloc_frag);
 869
 870 static void page_pool_empty_ring(struct page_pool *pool)
 871 {
 872         struct page *page;
 873
 874         /* Empty recycle ring */
 875         while ((page = ptr_ring_consume_bh(&pool->ring))) {
 876                 /* Verify the refcnt invariant of cached pages */
 877                 if (!(page_ref_count(page) == 1))
 878                         pr_crit("%s() page_pool refcnt %d violation\n",
 879                                 __func__, page_ref_count(page));
 880
 881                 page_pool_return_page(pool, page);
 882         }
 883 }
 884
 885 static void __page_pool_destroy(struct page_pool *pool)
 886 {
 887         if (pool->disconnect)
 888                 pool->disconnect(pool);
 889
 890         page_pool_unlist(pool);
 891         page_pool_uninit(pool);
 892         kfree(pool);
 893 }
 894
 895 static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
 896 {
 897         struct page *page;
 898
 899         if (pool->destroy_cnt)
 900                 return;
 901
 902         /* Empty alloc cache, assume caller made sure this is
 903          * no-longer in use, and page_pool_alloc_pages() cannot be
 904          * call concurrently.
 905          */
 906         while (pool->alloc.count) {
 907                 page = pool->alloc.cache[--pool->alloc.count];
 908                 page_pool_return_page(pool, page);
 909         }
 910 }
 911
 912 static void page_pool_scrub(struct page_pool *pool)
 913 {
 914         page_pool_empty_alloc_cache_once(pool);
 915         pool->destroy_cnt++;
 916
 917         /* No more consumers should exist, but producers could still
 918          * be in-flight.
 919          */
 920         page_pool_empty_ring(pool);
 921 }
 922
 923 static int page_pool_release(struct page_pool *pool)
 924 {
 925         int inflight;
 926
 927         page_pool_scrub(pool);
 928         inflight = page_pool_inflight(pool, true);
 929         if (!inflight)
 930                 __page_pool_destroy(pool);
 931
 932         return inflight;
 933 }
 934
 935 static void page_pool_release_retry(struct work_struct *wq)
 936 {
 937         struct delayed_work *dwq = to_delayed_work(wq);
 938         struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
 939         void *netdev;
 940         int inflight;
 941
 942         inflight = page_pool_release(pool);
 943         if (!inflight)
 944                 return;
 945
 946         /* Periodic warning for page pools the user can't see */
 947         netdev = READ_ONCE(pool->slow.netdev);
 948         if (time_after_eq(jiffies, pool->defer_warn) &&
 949             (!netdev || netdev == NET_PTR_POISON)) {
 950                 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
 951
 952                 pr_warn("%s() stalled pool shutdown: id %u, %d inflight %d sec\n",
 953                         __func__, pool->user.id, inflight, sec);
 954                 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
 955         }
 956
 957         /* Still not ready to be disconnected, retry later */
 958         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 959 }
 960
 961 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
 962                            struct xdp_mem_info *mem)
 963 {
 964         refcount_inc(&pool->user_cnt);
 965         pool->disconnect = disconnect;
 966         pool->xdp_mem_id = mem->id;
 967 }
 968
 969 static void page_pool_disable_direct_recycling(struct page_pool *pool)
 970 {
 971         /* Disable direct recycling based on pool->cpuid.
 972          * Paired with READ_ONCE() in napi_pp_put_page().
 973          */
 974         WRITE_ONCE(pool->cpuid, -1);
 975
 976         if (!pool->p.napi)
 977                 return;
 978
 979         /* To avoid races with recycling and additional barriers make sure
 980          * pool and NAPI are unlinked when NAPI is disabled.
 981          */
 982         WARN_ON(!test_bit(NAPI_STATE_SCHED, &pool->p.napi->state) ||
 983                 READ_ONCE(pool->p.napi->list_owner) != -1);
 984
 985         WRITE_ONCE(pool->p.napi, NULL);
 986 }
 987
 988 void page_pool_destroy(struct page_pool *pool)
 989 {
 990         if (!pool)
 991                 return;
 992
 993         if (!page_pool_put(pool))
 994                 return;
 995
 996         page_pool_disable_direct_recycling(pool);
 997         page_pool_free_frag(pool);
 998
 999         if (!page_pool_release(pool))
1000                 return;
1001
1002         page_pool_detached(pool);
1003         pool->defer_start = jiffies;
1004         pool->defer_warn  = jiffies + DEFER_WARN_INTERVAL;
1005
1006         INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
1007         schedule_delayed_work(&pool->release_dw, DEFER_TIME);
1008 }
1009 EXPORT_SYMBOL(page_pool_destroy);
1010
1011 /* Caller must provide appropriate safe context, e.g. NAPI. */
1012 void page_pool_update_nid(struct page_pool *pool, int new_nid)
1013 {
1014         struct page *page;
1015
1016         trace_page_pool_update_nid(pool, new_nid);
1017         pool->p.nid = new_nid;
1018
1019         /* Flush pool alloc cache, as refill will check NUMA node */
1020         while (pool->alloc.count) {
1021                 page = pool->alloc.cache[--pool->alloc.count];
1022                 page_pool_return_page(pool, page);
1023         }
1024 }
1025 EXPORT_SYMBOL(page_pool_update_nid);