1 /* SPDX-License-Identifier: GPL-2.0
4 * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
5 * Copyright (C) 2016 Red Hat, Inc.
8 #include <linux/types.h>
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/device.h>
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() */
19 #include <trace/events/page_pool.h>
21 #define DEFER_TIME (msecs_to_jiffies(1000))
22 #define DEFER_WARN_INTERVAL (60 * HZ)
24 static int page_pool_init(struct page_pool *pool,
25 const struct page_pool_params *params)
27 unsigned int ring_qsize = 1024; /* Default */
29 memcpy(&pool->p, params, sizeof(pool->p));
31 /* Validate only known flags were used */
32 if (pool->p.flags & ~(PP_FLAG_ALL))
35 if (pool->p.pool_size)
36 ring_qsize = pool->p.pool_size;
38 /* Sanity limit mem that can be pinned down */
39 if (ring_qsize > 32768)
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.
46 if (pool->p.flags & PP_FLAG_DMA_MAP) {
47 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
48 (pool->p.dma_dir != DMA_BIDIRECTIONAL))
52 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
53 /* In order to request DMA-sync-for-device the page
56 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
62 /* pool->p.offset has to be set according to the address
63 * offset used by the DMA engine to start copying rx data
67 if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
70 atomic_set(&pool->pages_state_release_cnt, 0);
72 /* Driver calling page_pool_create() also call page_pool_destroy() */
73 refcount_set(&pool->user_cnt, 1);
75 if (pool->p.flags & PP_FLAG_DMA_MAP)
76 get_device(pool->p.dev);
81 struct page_pool *page_pool_create(const struct page_pool_params *params)
83 struct page_pool *pool;
86 pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
88 return ERR_PTR(-ENOMEM);
90 err = page_pool_init(pool, params);
92 pr_warn("%s() gave up with errno %d\n", __func__, err);
99 EXPORT_SYMBOL(page_pool_create);
101 static void page_pool_return_page(struct page_pool *pool, struct page *page);
104 static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
106 struct ptr_ring *r = &pool->ring;
108 int pref_nid; /* preferred NUMA node */
110 /* Quicker fallback, avoid locks when ring is empty */
111 if (__ptr_ring_empty(r))
114 /* Softirq guarantee CPU and thus NUMA node is stable. This,
115 * assumes CPU refilling driver RX-ring will also run RX-NAPI.
118 pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
120 /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
121 pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
124 /* Slower-path: Get pages from locked ring queue */
125 spin_lock(&r->consumer_lock);
127 /* Refill alloc array, but only if NUMA match */
129 page = __ptr_ring_consume(r);
133 if (likely(page_to_nid(page) == pref_nid)) {
134 pool->alloc.cache[pool->alloc.count++] = page;
137 * (1) release 1 page to page-allocator and
138 * (2) break out to fallthrough to alloc_pages_node.
139 * This limit stress on page buddy alloactor.
141 page_pool_return_page(pool, page);
145 } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
147 /* Return last page */
148 if (likely(pool->alloc.count > 0))
149 page = pool->alloc.cache[--pool->alloc.count];
151 spin_unlock(&r->consumer_lock);
156 static struct page *__page_pool_get_cached(struct page_pool *pool)
160 /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
161 if (likely(pool->alloc.count)) {
163 page = pool->alloc.cache[--pool->alloc.count];
165 page = page_pool_refill_alloc_cache(pool);
171 static void page_pool_dma_sync_for_device(struct page_pool *pool,
173 unsigned int dma_sync_size)
175 dma_addr_t dma_addr = page_pool_get_dma_addr(page);
177 dma_sync_size = min(dma_sync_size, pool->p.max_len);
178 dma_sync_single_range_for_device(pool->p.dev, dma_addr,
179 pool->p.offset, dma_sync_size,
185 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
192 /* We could always set __GFP_COMP, and avoid this branch, as
193 * prep_new_page() can handle order-0 with __GFP_COMP.
198 /* FUTURE development:
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.
205 /* Cache was empty, do real allocation */
207 page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
209 page = alloc_pages(gfp, pool->p.order);
214 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
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.
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)) {
229 page_pool_set_dma_addr(page, dma);
231 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
232 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
235 /* Track how many pages are held 'in-flight' */
236 pool->pages_state_hold_cnt++;
238 trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
240 /* When page just alloc'ed is should/must have refcnt 1. */
244 /* For using page_pool replace: alloc_pages() API calls, but provide
245 * synchronization guarantee for allocation side.
247 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
251 /* Fast-path: Get a page from cache */
252 page = __page_pool_get_cached(pool);
256 /* Slow-path: cache empty, do real allocation */
257 page = __page_pool_alloc_pages_slow(pool, gfp);
260 EXPORT_SYMBOL(page_pool_alloc_pages);
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
265 #define _distance(a, b) (s32)((a) - (b))
267 static s32 page_pool_inflight(struct page_pool *pool)
269 u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
270 u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
273 inflight = _distance(hold_cnt, release_cnt);
275 trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
276 WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
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).
286 void page_pool_release_page(struct page_pool *pool, struct page *page)
291 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
292 /* Always account for inflight pages, even if we didn't
297 dma = page_pool_get_dma_addr(page);
299 /* When page is unmapped, it cannot be returned to 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_pool_set_dma_addr(page, 0);
305 /* This may be the last page returned, releasing the pool, so
306 * it is not safe to reference pool afterwards.
308 count = atomic_inc_return(&pool->pages_state_release_cnt);
309 trace_page_pool_state_release(pool, page, count);
311 EXPORT_SYMBOL(page_pool_release_page);
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)
316 page_pool_release_page(pool, 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).
325 static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
328 /* BH protection not needed if current is serving softirq */
329 if (in_serving_softirq())
330 ret = ptr_ring_produce(&pool->ring, page);
332 ret = ptr_ring_produce_bh(&pool->ring, page);
334 return (ret == 0) ? true : false;
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.
340 * Caller must provide appropriate safe context.
342 static bool page_pool_recycle_in_cache(struct page *page,
343 struct page_pool *pool)
345 if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
348 /* Caller MUST have verified/know (page_ref_count(page) == 1) */
349 pool->alloc.cache[pool->alloc.count++] = page;
353 /* page is NOT reusable when:
354 * 1) allocated when system is under some pressure. (page_is_pfmemalloc)
356 static bool pool_page_reusable(struct page_pool *pool, struct page *page)
358 return !page_is_pfmemalloc(page);
361 /* If the page refcnt == 1, this will try to recycle the page.
362 * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
363 * the configured size min(dma_sync_size, pool->max_len).
364 * If the page refcnt != 1, then the page will be returned to memory
367 void page_pool_put_page(struct page_pool *pool, struct page *page,
368 unsigned int dma_sync_size, bool allow_direct)
370 /* This allocator is optimized for the XDP mode that uses
371 * one-frame-per-page, but have fallbacks that act like the
372 * regular page allocator APIs.
374 * refcnt == 1 means page_pool owns page, and can recycle it.
376 if (likely(page_ref_count(page) == 1 &&
377 pool_page_reusable(pool, page))) {
378 /* Read barrier done in page_ref_count / READ_ONCE */
380 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
381 page_pool_dma_sync_for_device(pool, page,
384 if (allow_direct && in_serving_softirq())
385 if (page_pool_recycle_in_cache(page, pool))
388 if (!page_pool_recycle_in_ring(pool, page)) {
389 /* Cache full, fallback to free pages */
390 page_pool_return_page(pool, page);
394 /* Fallback/non-XDP mode: API user have elevated refcnt.
396 * Many drivers split up the page into fragments, and some
397 * want to keep doing this to save memory and do refcnt based
398 * recycling. Support this use case too, to ease drivers
399 * switching between XDP/non-XDP.
401 * In-case page_pool maintains the DMA mapping, API user must
402 * call page_pool_put_page once. In this elevated refcnt
403 * case, the DMA is unmapped/released, as driver is likely
404 * doing refcnt based recycle tricks, meaning another process
405 * will be invoking put_page.
407 /* Do not replace this with page_pool_return_page() */
408 page_pool_release_page(pool, page);
411 EXPORT_SYMBOL(page_pool_put_page);
413 static void page_pool_empty_ring(struct page_pool *pool)
417 /* Empty recycle ring */
418 while ((page = ptr_ring_consume_bh(&pool->ring))) {
419 /* Verify the refcnt invariant of cached pages */
420 if (!(page_ref_count(page) == 1))
421 pr_crit("%s() page_pool refcnt %d violation\n",
422 __func__, page_ref_count(page));
424 page_pool_return_page(pool, page);
428 static void page_pool_free(struct page_pool *pool)
430 if (pool->disconnect)
431 pool->disconnect(pool);
433 ptr_ring_cleanup(&pool->ring, NULL);
435 if (pool->p.flags & PP_FLAG_DMA_MAP)
436 put_device(pool->p.dev);
441 static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
445 if (pool->destroy_cnt)
448 /* Empty alloc cache, assume caller made sure this is
449 * no-longer in use, and page_pool_alloc_pages() cannot be
452 while (pool->alloc.count) {
453 page = pool->alloc.cache[--pool->alloc.count];
454 page_pool_return_page(pool, page);
458 static void page_pool_scrub(struct page_pool *pool)
460 page_pool_empty_alloc_cache_once(pool);
463 /* No more consumers should exist, but producers could still
466 page_pool_empty_ring(pool);
469 static int page_pool_release(struct page_pool *pool)
473 page_pool_scrub(pool);
474 inflight = page_pool_inflight(pool);
476 page_pool_free(pool);
481 static void page_pool_release_retry(struct work_struct *wq)
483 struct delayed_work *dwq = to_delayed_work(wq);
484 struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
487 inflight = page_pool_release(pool);
491 /* Periodic warning */
492 if (time_after_eq(jiffies, pool->defer_warn)) {
493 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
495 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
496 __func__, inflight, sec);
497 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
500 /* Still not ready to be disconnected, retry later */
501 schedule_delayed_work(&pool->release_dw, DEFER_TIME);
504 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
506 refcount_inc(&pool->user_cnt);
507 pool->disconnect = disconnect;
510 void page_pool_destroy(struct page_pool *pool)
515 if (!page_pool_put(pool))
518 if (!page_pool_release(pool))
521 pool->defer_start = jiffies;
522 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
524 INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
525 schedule_delayed_work(&pool->release_dw, DEFER_TIME);
527 EXPORT_SYMBOL(page_pool_destroy);
529 /* Caller must provide appropriate safe context, e.g. NAPI. */
530 void page_pool_update_nid(struct page_pool *pool, int new_nid)
534 trace_page_pool_update_nid(pool, new_nid);
535 pool->p.nid = new_nid;
537 /* Flush pool alloc cache, as refill will check NUMA node */
538 while (pool->alloc.count) {
539 page = pool->alloc.cache[--pool->alloc.count];
540 page_pool_return_page(pool, page);
543 EXPORT_SYMBOL(page_pool_update_nid);