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1/* SPDX-License-Identifier: GPL-2.0
2 *
3 * page_pool.c
4 * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
5 * Copyright (C) 2016 Red Hat, Inc.
6 */
7
8#include <linux/types.h>
9#include <linux/kernel.h>
10#include <linux/slab.h>
11#include <linux/device.h>
12
13#include <net/page_pool.h>
14#include <linux/dma-direction.h>
15#include <linux/dma-mapping.h>
16#include <linux/page-flags.h>
17#include <linux/mm.h> /* for __put_page() */
18
19#include <trace/events/page_pool.h>
20
21static int page_pool_init(struct page_pool *pool,
22 const struct page_pool_params *params)
23{
24 unsigned int ring_qsize = 1024; /* Default */
25
26 memcpy(&pool->p, params, sizeof(pool->p));
27
28 /* Validate only known flags were used */
29 if (pool->p.flags & ~(PP_FLAG_ALL))
30 return -EINVAL;
31
32 if (pool->p.pool_size)
33 ring_qsize = pool->p.pool_size;
34
35 /* Sanity limit mem that can be pinned down */
36 if (ring_qsize > 32768)
37 return -E2BIG;
38
39 /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
40 * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
41 * which is the XDP_TX use-case.
42 */
43 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
44 (pool->p.dma_dir != DMA_BIDIRECTIONAL))
45 return -EINVAL;
46
47 if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
48 return -ENOMEM;
49
50 atomic_set(&pool->pages_state_release_cnt, 0);
51
52 /* Driver calling page_pool_create() also call page_pool_destroy() */
53 refcount_set(&pool->user_cnt, 1);
54
55 if (pool->p.flags & PP_FLAG_DMA_MAP)
56 get_device(pool->p.dev);
57
58 return 0;
59}
60
61struct page_pool *page_pool_create(const struct page_pool_params *params)
62{
63 struct page_pool *pool;
64 int err;
65
66 pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
67 if (!pool)
68 return ERR_PTR(-ENOMEM);
69
70 err = page_pool_init(pool, params);
71 if (err < 0) {
72 pr_warn("%s() gave up with errno %d\n", __func__, err);
73 kfree(pool);
74 return ERR_PTR(err);
75 }
76
77 return pool;
78}
79EXPORT_SYMBOL(page_pool_create);
80
81/* fast path */
82static struct page *__page_pool_get_cached(struct page_pool *pool)
83{
84 struct ptr_ring *r = &pool->ring;
85 bool refill = false;
86 struct page *page;
87
88 /* Test for safe-context, caller should provide this guarantee */
89 if (likely(in_serving_softirq())) {
90 if (likely(pool->alloc.count)) {
91 /* Fast-path */
92 page = pool->alloc.cache[--pool->alloc.count];
93 return page;
94 }
95 refill = true;
96 }
97
98 /* Quicker fallback, avoid locks when ring is empty */
99 if (__ptr_ring_empty(r))
100 return NULL;
101
102 /* Slow-path: Get page from locked ring queue,
103 * refill alloc array if requested.
104 */
105 spin_lock(&r->consumer_lock);
106 page = __ptr_ring_consume(r);
107 if (refill)
108 pool->alloc.count = __ptr_ring_consume_batched(r,
109 pool->alloc.cache,
110 PP_ALLOC_CACHE_REFILL);
111 spin_unlock(&r->consumer_lock);
112 return page;
113}
114
115/* slow path */
116noinline
117static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
118 gfp_t _gfp)
119{
120 struct page *page;
121 gfp_t gfp = _gfp;
122 dma_addr_t dma;
123
124 /* We could always set __GFP_COMP, and avoid this branch, as
125 * prep_new_page() can handle order-0 with __GFP_COMP.
126 */
127 if (pool->p.order)
128 gfp |= __GFP_COMP;
129
130 /* FUTURE development:
131 *
132 * Current slow-path essentially falls back to single page
133 * allocations, which doesn't improve performance. This code
134 * need bulk allocation support from the page allocator code.
135 */
136
137 /* Cache was empty, do real allocation */
138 page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
139 if (!page)
140 return NULL;
141
142 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
143 goto skip_dma_map;
144
145 /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
146 * since dma_addr_t can be either 32 or 64 bits and does not always fit
147 * into page private data (i.e 32bit cpu with 64bit DMA caps)
148 * This mapping is kept for lifetime of page, until leaving pool.
149 */
150 dma = dma_map_page_attrs(pool->p.dev, page, 0,
151 (PAGE_SIZE << pool->p.order),
152 pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
153 if (dma_mapping_error(pool->p.dev, dma)) {
154 put_page(page);
155 return NULL;
156 }
157 page->dma_addr = dma;
158
159skip_dma_map:
160 /* Track how many pages are held 'in-flight' */
161 pool->pages_state_hold_cnt++;
162
163 trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
164
165 /* When page just alloc'ed is should/must have refcnt 1. */
166 return page;
167}
168
169/* For using page_pool replace: alloc_pages() API calls, but provide
170 * synchronization guarantee for allocation side.
171 */
172struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
173{
174 struct page *page;
175
176 /* Fast-path: Get a page from cache */
177 page = __page_pool_get_cached(pool);
178 if (page)
179 return page;
180
181 /* Slow-path: cache empty, do real allocation */
182 page = __page_pool_alloc_pages_slow(pool, gfp);
183 return page;
184}
185EXPORT_SYMBOL(page_pool_alloc_pages);
186
187/* Calculate distance between two u32 values, valid if distance is below 2^(31)
188 * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
189 */
190#define _distance(a, b) (s32)((a) - (b))
191
192static s32 page_pool_inflight(struct page_pool *pool)
193{
194 u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
195 u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
196 s32 distance;
197
198 distance = _distance(hold_cnt, release_cnt);
199
200 trace_page_pool_inflight(pool, distance, hold_cnt, release_cnt);
201 return distance;
202}
203
204static bool __page_pool_safe_to_destroy(struct page_pool *pool)
205{
206 s32 inflight = page_pool_inflight(pool);
207
208 /* The distance should not be able to become negative */
209 WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
210
211 return (inflight == 0);
212}
213
214/* Cleanup page_pool state from page */
215static void __page_pool_clean_page(struct page_pool *pool,
216 struct page *page)
217{
218 dma_addr_t dma;
219
220 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
221 goto skip_dma_unmap;
222
223 dma = page->dma_addr;
224 /* DMA unmap */
225 dma_unmap_page_attrs(pool->p.dev, dma,
226 PAGE_SIZE << pool->p.order, pool->p.dma_dir,
227 DMA_ATTR_SKIP_CPU_SYNC);
228 page->dma_addr = 0;
229skip_dma_unmap:
230 atomic_inc(&pool->pages_state_release_cnt);
231 trace_page_pool_state_release(pool, page,
232 atomic_read(&pool->pages_state_release_cnt));
233}
234
235/* unmap the page and clean our state */
236void page_pool_unmap_page(struct page_pool *pool, struct page *page)
237{
238 /* When page is unmapped, this implies page will not be
239 * returned to page_pool.
240 */
241 __page_pool_clean_page(pool, page);
242}
243EXPORT_SYMBOL(page_pool_unmap_page);
244
245/* Return a page to the page allocator, cleaning up our state */
246static void __page_pool_return_page(struct page_pool *pool, struct page *page)
247{
248 __page_pool_clean_page(pool, page);
249
250 put_page(page);
251 /* An optimization would be to call __free_pages(page, pool->p.order)
252 * knowing page is not part of page-cache (thus avoiding a
253 * __page_cache_release() call).
254 */
255}
256
257static bool __page_pool_recycle_into_ring(struct page_pool *pool,
258 struct page *page)
259{
260 int ret;
261 /* BH protection not needed if current is serving softirq */
262 if (in_serving_softirq())
263 ret = ptr_ring_produce(&pool->ring, page);
264 else
265 ret = ptr_ring_produce_bh(&pool->ring, page);
266
267 return (ret == 0) ? true : false;
268}
269
270/* Only allow direct recycling in special circumstances, into the
271 * alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case.
272 *
273 * Caller must provide appropriate safe context.
274 */
275static bool __page_pool_recycle_direct(struct page *page,
276 struct page_pool *pool)
277{
278 if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
279 return false;
280
281 /* Caller MUST have verified/know (page_ref_count(page) == 1) */
282 pool->alloc.cache[pool->alloc.count++] = page;
283 return true;
284}
285
286void __page_pool_put_page(struct page_pool *pool,
287 struct page *page, bool allow_direct)
288{
289 /* This allocator is optimized for the XDP mode that uses
290 * one-frame-per-page, but have fallbacks that act like the
291 * regular page allocator APIs.
292 *
293 * refcnt == 1 means page_pool owns page, and can recycle it.
294 */
295 if (likely(page_ref_count(page) == 1)) {
296 /* Read barrier done in page_ref_count / READ_ONCE */
297
298 if (allow_direct && in_serving_softirq())
299 if (__page_pool_recycle_direct(page, pool))
300 return;
301
302 if (!__page_pool_recycle_into_ring(pool, page)) {
303 /* Cache full, fallback to free pages */
304 __page_pool_return_page(pool, page);
305 }
306 return;
307 }
308 /* Fallback/non-XDP mode: API user have elevated refcnt.
309 *
310 * Many drivers split up the page into fragments, and some
311 * want to keep doing this to save memory and do refcnt based
312 * recycling. Support this use case too, to ease drivers
313 * switching between XDP/non-XDP.
314 *
315 * In-case page_pool maintains the DMA mapping, API user must
316 * call page_pool_put_page once. In this elevated refcnt
317 * case, the DMA is unmapped/released, as driver is likely
318 * doing refcnt based recycle tricks, meaning another process
319 * will be invoking put_page.
320 */
321 __page_pool_clean_page(pool, page);
322 put_page(page);
323}
324EXPORT_SYMBOL(__page_pool_put_page);
325
326static void __page_pool_empty_ring(struct page_pool *pool)
327{
328 struct page *page;
329
330 /* Empty recycle ring */
331 while ((page = ptr_ring_consume_bh(&pool->ring))) {
332 /* Verify the refcnt invariant of cached pages */
333 if (!(page_ref_count(page) == 1))
334 pr_crit("%s() page_pool refcnt %d violation\n",
335 __func__, page_ref_count(page));
336
337 __page_pool_return_page(pool, page);
338 }
339}
340
341static void __warn_in_flight(struct page_pool *pool)
342{
343 u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
344 u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
345 s32 distance;
346
347 distance = _distance(hold_cnt, release_cnt);
348
349 /* Drivers should fix this, but only problematic when DMA is used */
350 WARN(1, "Still in-flight pages:%d hold:%u released:%u",
351 distance, hold_cnt, release_cnt);
352}
353
354void __page_pool_free(struct page_pool *pool)
355{
356 /* Only last user actually free/release resources */
357 if (!page_pool_put(pool))
358 return;
359
360 WARN(pool->alloc.count, "API usage violation");
361 WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty");
362
363 /* Can happen due to forced shutdown */
364 if (!__page_pool_safe_to_destroy(pool))
365 __warn_in_flight(pool);
366
367 ptr_ring_cleanup(&pool->ring, NULL);
368
369 if (pool->p.flags & PP_FLAG_DMA_MAP)
370 put_device(pool->p.dev);
371
372 kfree(pool);
373}
374EXPORT_SYMBOL(__page_pool_free);
375
376/* Request to shutdown: release pages cached by page_pool, and check
377 * for in-flight pages
378 */
379bool __page_pool_request_shutdown(struct page_pool *pool)
380{
381 struct page *page;
382
383 /* Empty alloc cache, assume caller made sure this is
384 * no-longer in use, and page_pool_alloc_pages() cannot be
385 * call concurrently.
386 */
387 while (pool->alloc.count) {
388 page = pool->alloc.cache[--pool->alloc.count];
389 __page_pool_return_page(pool, page);
390 }
391
392 /* No more consumers should exist, but producers could still
393 * be in-flight.
394 */
395 __page_pool_empty_ring(pool);
396
397 return __page_pool_safe_to_destroy(pool);
398}
399EXPORT_SYMBOL(__page_pool_request_shutdown);
1/* SPDX-License-Identifier: GPL-2.0
2 *
3 * page_pool.c
4 * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
5 * Copyright (C) 2016 Red Hat, Inc.
6 */
7
8#include <linux/types.h>
9#include <linux/kernel.h>
10#include <linux/slab.h>
11#include <linux/device.h>
12
13#include <net/page_pool.h>
14#include <linux/dma-direction.h>
15#include <linux/dma-mapping.h>
16#include <linux/page-flags.h>
17#include <linux/mm.h> /* for __put_page() */
18
19#include <trace/events/page_pool.h>
20
21#define DEFER_TIME (msecs_to_jiffies(1000))
22#define DEFER_WARN_INTERVAL (60 * HZ)
23
24static int page_pool_init(struct page_pool *pool,
25 const struct page_pool_params *params)
26{
27 unsigned int ring_qsize = 1024; /* Default */
28
29 memcpy(&pool->p, params, sizeof(pool->p));
30
31 /* Validate only known flags were used */
32 if (pool->p.flags & ~(PP_FLAG_ALL))
33 return -EINVAL;
34
35 if (pool->p.pool_size)
36 ring_qsize = pool->p.pool_size;
37
38 /* Sanity limit mem that can be pinned down */
39 if (ring_qsize > 32768)
40 return -E2BIG;
41
42 /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
43 * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
44 * which is the XDP_TX use-case.
45 */
46 if (pool->p.flags & PP_FLAG_DMA_MAP) {
47 if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
48 (pool->p.dma_dir != DMA_BIDIRECTIONAL))
49 return -EINVAL;
50 }
51
52 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
53 /* In order to request DMA-sync-for-device the page
54 * needs to be mapped
55 */
56 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
57 return -EINVAL;
58
59 if (!pool->p.max_len)
60 return -EINVAL;
61
62 /* pool->p.offset has to be set according to the address
63 * offset used by the DMA engine to start copying rx data
64 */
65 }
66
67 if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
68 return -ENOMEM;
69
70 atomic_set(&pool->pages_state_release_cnt, 0);
71
72 /* Driver calling page_pool_create() also call page_pool_destroy() */
73 refcount_set(&pool->user_cnt, 1);
74
75 if (pool->p.flags & PP_FLAG_DMA_MAP)
76 get_device(pool->p.dev);
77
78 return 0;
79}
80
81struct page_pool *page_pool_create(const struct page_pool_params *params)
82{
83 struct page_pool *pool;
84 int err;
85
86 pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
87 if (!pool)
88 return ERR_PTR(-ENOMEM);
89
90 err = page_pool_init(pool, params);
91 if (err < 0) {
92 pr_warn("%s() gave up with errno %d\n", __func__, err);
93 kfree(pool);
94 return ERR_PTR(err);
95 }
96
97 return pool;
98}
99EXPORT_SYMBOL(page_pool_create);
100
101static void page_pool_return_page(struct page_pool *pool, struct page *page);
102
103noinline
104static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
105{
106 struct ptr_ring *r = &pool->ring;
107 struct page *page;
108 int pref_nid; /* preferred NUMA node */
109
110 /* Quicker fallback, avoid locks when ring is empty */
111 if (__ptr_ring_empty(r))
112 return NULL;
113
114 /* Softirq guarantee CPU and thus NUMA node is stable. This,
115 * assumes CPU refilling driver RX-ring will also run RX-NAPI.
116 */
117#ifdef CONFIG_NUMA
118 pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
119#else
120 /* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
121 pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
122#endif
123
124 /* Slower-path: Get pages from locked ring queue */
125 spin_lock(&r->consumer_lock);
126
127 /* Refill alloc array, but only if NUMA match */
128 do {
129 page = __ptr_ring_consume(r);
130 if (unlikely(!page))
131 break;
132
133 if (likely(page_to_nid(page) == pref_nid)) {
134 pool->alloc.cache[pool->alloc.count++] = page;
135 } else {
136 /* NUMA mismatch;
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.
140 */
141 page_pool_return_page(pool, page);
142 page = NULL;
143 break;
144 }
145 } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
146
147 /* Return last page */
148 if (likely(pool->alloc.count > 0))
149 page = pool->alloc.cache[--pool->alloc.count];
150
151 spin_unlock(&r->consumer_lock);
152 return page;
153}
154
155/* fast path */
156static struct page *__page_pool_get_cached(struct page_pool *pool)
157{
158 struct page *page;
159
160 /* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
161 if (likely(pool->alloc.count)) {
162 /* Fast-path */
163 page = pool->alloc.cache[--pool->alloc.count];
164 } else {
165 page = page_pool_refill_alloc_cache(pool);
166 }
167
168 return page;
169}
170
171static void page_pool_dma_sync_for_device(struct page_pool *pool,
172 struct page *page,
173 unsigned int dma_sync_size)
174{
175 dma_sync_size = min(dma_sync_size, pool->p.max_len);
176 dma_sync_single_range_for_device(pool->p.dev, page->dma_addr,
177 pool->p.offset, dma_sync_size,
178 pool->p.dma_dir);
179}
180
181/* slow path */
182noinline
183static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
184 gfp_t _gfp)
185{
186 struct page *page;
187 gfp_t gfp = _gfp;
188 dma_addr_t dma;
189
190 /* We could always set __GFP_COMP, and avoid this branch, as
191 * prep_new_page() can handle order-0 with __GFP_COMP.
192 */
193 if (pool->p.order)
194 gfp |= __GFP_COMP;
195
196 /* FUTURE development:
197 *
198 * Current slow-path essentially falls back to single page
199 * allocations, which doesn't improve performance. This code
200 * need bulk allocation support from the page allocator code.
201 */
202
203 /* Cache was empty, do real allocation */
204#ifdef CONFIG_NUMA
205 page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
206#else
207 page = alloc_pages(gfp, pool->p.order);
208#endif
209 if (!page)
210 return NULL;
211
212 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
213 goto skip_dma_map;
214
215 /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
216 * since dma_addr_t can be either 32 or 64 bits and does not always fit
217 * into page private data (i.e 32bit cpu with 64bit DMA caps)
218 * This mapping is kept for lifetime of page, until leaving pool.
219 */
220 dma = dma_map_page_attrs(pool->p.dev, page, 0,
221 (PAGE_SIZE << pool->p.order),
222 pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
223 if (dma_mapping_error(pool->p.dev, dma)) {
224 put_page(page);
225 return NULL;
226 }
227 page->dma_addr = dma;
228
229 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
230 page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
231
232skip_dma_map:
233 /* Track how many pages are held 'in-flight' */
234 pool->pages_state_hold_cnt++;
235
236 trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
237
238 /* When page just alloc'ed is should/must have refcnt 1. */
239 return page;
240}
241
242/* For using page_pool replace: alloc_pages() API calls, but provide
243 * synchronization guarantee for allocation side.
244 */
245struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
246{
247 struct page *page;
248
249 /* Fast-path: Get a page from cache */
250 page = __page_pool_get_cached(pool);
251 if (page)
252 return page;
253
254 /* Slow-path: cache empty, do real allocation */
255 page = __page_pool_alloc_pages_slow(pool, gfp);
256 return page;
257}
258EXPORT_SYMBOL(page_pool_alloc_pages);
259
260/* Calculate distance between two u32 values, valid if distance is below 2^(31)
261 * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
262 */
263#define _distance(a, b) (s32)((a) - (b))
264
265static s32 page_pool_inflight(struct page_pool *pool)
266{
267 u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
268 u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
269 s32 inflight;
270
271 inflight = _distance(hold_cnt, release_cnt);
272
273 trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
274 WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);
275
276 return inflight;
277}
278
279/* Disconnects a page (from a page_pool). API users can have a need
280 * to disconnect a page (from a page_pool), to allow it to be used as
281 * a regular page (that will eventually be returned to the normal
282 * page-allocator via put_page).
283 */
284void page_pool_release_page(struct page_pool *pool, struct page *page)
285{
286 dma_addr_t dma;
287 int count;
288
289 if (!(pool->p.flags & PP_FLAG_DMA_MAP))
290 /* Always account for inflight pages, even if we didn't
291 * map them
292 */
293 goto skip_dma_unmap;
294
295 dma = page->dma_addr;
296
297 /* When page is unmapped, it cannot be returned our pool */
298 dma_unmap_page_attrs(pool->p.dev, dma,
299 PAGE_SIZE << pool->p.order, pool->p.dma_dir,
300 DMA_ATTR_SKIP_CPU_SYNC);
301 page->dma_addr = 0;
302skip_dma_unmap:
303 /* This may be the last page returned, releasing the pool, so
304 * it is not safe to reference pool afterwards.
305 */
306 count = atomic_inc_return(&pool->pages_state_release_cnt);
307 trace_page_pool_state_release(pool, page, count);
308}
309EXPORT_SYMBOL(page_pool_release_page);
310
311/* Return a page to the page allocator, cleaning up our state */
312static void page_pool_return_page(struct page_pool *pool, struct page *page)
313{
314 page_pool_release_page(pool, page);
315
316 put_page(page);
317 /* An optimization would be to call __free_pages(page, pool->p.order)
318 * knowing page is not part of page-cache (thus avoiding a
319 * __page_cache_release() call).
320 */
321}
322
323static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
324{
325 int ret;
326 /* BH protection not needed if current is serving softirq */
327 if (in_serving_softirq())
328 ret = ptr_ring_produce(&pool->ring, page);
329 else
330 ret = ptr_ring_produce_bh(&pool->ring, page);
331
332 return (ret == 0) ? true : false;
333}
334
335/* Only allow direct recycling in special circumstances, into the
336 * alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case.
337 *
338 * Caller must provide appropriate safe context.
339 */
340static bool page_pool_recycle_in_cache(struct page *page,
341 struct page_pool *pool)
342{
343 if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
344 return false;
345
346 /* Caller MUST have verified/know (page_ref_count(page) == 1) */
347 pool->alloc.cache[pool->alloc.count++] = page;
348 return true;
349}
350
351/* page is NOT reusable when:
352 * 1) allocated when system is under some pressure. (page_is_pfmemalloc)
353 */
354static bool pool_page_reusable(struct page_pool *pool, struct page *page)
355{
356 return !page_is_pfmemalloc(page);
357}
358
359/* If the page refcnt == 1, this will try to recycle the page.
360 * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
361 * the configured size min(dma_sync_size, pool->max_len).
362 * If the page refcnt != 1, then the page will be returned to memory
363 * subsystem.
364 */
365void page_pool_put_page(struct page_pool *pool, struct page *page,
366 unsigned int dma_sync_size, bool allow_direct)
367{
368 /* This allocator is optimized for the XDP mode that uses
369 * one-frame-per-page, but have fallbacks that act like the
370 * regular page allocator APIs.
371 *
372 * refcnt == 1 means page_pool owns page, and can recycle it.
373 */
374 if (likely(page_ref_count(page) == 1 &&
375 pool_page_reusable(pool, page))) {
376 /* Read barrier done in page_ref_count / READ_ONCE */
377
378 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
379 page_pool_dma_sync_for_device(pool, page,
380 dma_sync_size);
381
382 if (allow_direct && in_serving_softirq())
383 if (page_pool_recycle_in_cache(page, pool))
384 return;
385
386 if (!page_pool_recycle_in_ring(pool, page)) {
387 /* Cache full, fallback to free pages */
388 page_pool_return_page(pool, page);
389 }
390 return;
391 }
392 /* Fallback/non-XDP mode: API user have elevated refcnt.
393 *
394 * Many drivers split up the page into fragments, and some
395 * want to keep doing this to save memory and do refcnt based
396 * recycling. Support this use case too, to ease drivers
397 * switching between XDP/non-XDP.
398 *
399 * In-case page_pool maintains the DMA mapping, API user must
400 * call page_pool_put_page once. In this elevated refcnt
401 * case, the DMA is unmapped/released, as driver is likely
402 * doing refcnt based recycle tricks, meaning another process
403 * will be invoking put_page.
404 */
405 /* Do not replace this with page_pool_return_page() */
406 page_pool_release_page(pool, page);
407 put_page(page);
408}
409EXPORT_SYMBOL(page_pool_put_page);
410
411static void page_pool_empty_ring(struct page_pool *pool)
412{
413 struct page *page;
414
415 /* Empty recycle ring */
416 while ((page = ptr_ring_consume_bh(&pool->ring))) {
417 /* Verify the refcnt invariant of cached pages */
418 if (!(page_ref_count(page) == 1))
419 pr_crit("%s() page_pool refcnt %d violation\n",
420 __func__, page_ref_count(page));
421
422 page_pool_return_page(pool, page);
423 }
424}
425
426static void page_pool_free(struct page_pool *pool)
427{
428 if (pool->disconnect)
429 pool->disconnect(pool);
430
431 ptr_ring_cleanup(&pool->ring, NULL);
432
433 if (pool->p.flags & PP_FLAG_DMA_MAP)
434 put_device(pool->p.dev);
435
436 kfree(pool);
437}
438
439static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
440{
441 struct page *page;
442
443 if (pool->destroy_cnt)
444 return;
445
446 /* Empty alloc cache, assume caller made sure this is
447 * no-longer in use, and page_pool_alloc_pages() cannot be
448 * call concurrently.
449 */
450 while (pool->alloc.count) {
451 page = pool->alloc.cache[--pool->alloc.count];
452 page_pool_return_page(pool, page);
453 }
454}
455
456static void page_pool_scrub(struct page_pool *pool)
457{
458 page_pool_empty_alloc_cache_once(pool);
459 pool->destroy_cnt++;
460
461 /* No more consumers should exist, but producers could still
462 * be in-flight.
463 */
464 page_pool_empty_ring(pool);
465}
466
467static int page_pool_release(struct page_pool *pool)
468{
469 int inflight;
470
471 page_pool_scrub(pool);
472 inflight = page_pool_inflight(pool);
473 if (!inflight)
474 page_pool_free(pool);
475
476 return inflight;
477}
478
479static void page_pool_release_retry(struct work_struct *wq)
480{
481 struct delayed_work *dwq = to_delayed_work(wq);
482 struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
483 int inflight;
484
485 inflight = page_pool_release(pool);
486 if (!inflight)
487 return;
488
489 /* Periodic warning */
490 if (time_after_eq(jiffies, pool->defer_warn)) {
491 int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
492
493 pr_warn("%s() stalled pool shutdown %d inflight %d sec\n",
494 __func__, inflight, sec);
495 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
496 }
497
498 /* Still not ready to be disconnected, retry later */
499 schedule_delayed_work(&pool->release_dw, DEFER_TIME);
500}
501
502void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
503{
504 refcount_inc(&pool->user_cnt);
505 pool->disconnect = disconnect;
506}
507
508void page_pool_destroy(struct page_pool *pool)
509{
510 if (!pool)
511 return;
512
513 if (!page_pool_put(pool))
514 return;
515
516 if (!page_pool_release(pool))
517 return;
518
519 pool->defer_start = jiffies;
520 pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
521
522 INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
523 schedule_delayed_work(&pool->release_dw, DEFER_TIME);
524}
525EXPORT_SYMBOL(page_pool_destroy);
526
527/* Caller must provide appropriate safe context, e.g. NAPI. */
528void page_pool_update_nid(struct page_pool *pool, int new_nid)
529{
530 struct page *page;
531
532 trace_page_pool_update_nid(pool, new_nid);
533 pool->p.nid = new_nid;
534
535 /* Flush pool alloc cache, as refill will check NUMA node */
536 while (pool->alloc.count) {
537 page = pool->alloc.cache[--pool->alloc.count];
538 page_pool_return_page(pool, page);
539 }
540}
541EXPORT_SYMBOL(page_pool_update_nid);