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ff7d6b27 JDB |
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 | */ | |
32c28f7e | 7 | |
ff7d6b27 JDB |
8 | #include <linux/types.h> |
9 | #include <linux/kernel.h> | |
10 | #include <linux/slab.h> | |
f71fec47 | 11 | #include <linux/device.h> |
ff7d6b27 JDB |
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 | ||
32c28f7e JDB |
19 | #include <trace/events/page_pool.h> |
20 | ||
ff7d6b27 JDB |
21 | static 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 | ||
99c07c43 JDB |
50 | atomic_set(&pool->pages_state_release_cnt, 0); |
51 | ||
1da4bbef IK |
52 | /* Driver calling page_pool_create() also call page_pool_destroy() */ |
53 | refcount_set(&pool->user_cnt, 1); | |
54 | ||
f71fec47 JDB |
55 | if (pool->p.flags & PP_FLAG_DMA_MAP) |
56 | get_device(pool->p.dev); | |
57 | ||
ff7d6b27 JDB |
58 | return 0; |
59 | } | |
60 | ||
61 | struct page_pool *page_pool_create(const struct page_pool_params *params) | |
62 | { | |
63 | struct page_pool *pool; | |
64 | int err = 0; | |
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 | } | |
1da4bbef | 76 | |
ff7d6b27 JDB |
77 | return pool; |
78 | } | |
79 | EXPORT_SYMBOL(page_pool_create); | |
80 | ||
81 | /* fast path */ | |
82 | static struct page *__page_pool_get_cached(struct page_pool *pool) | |
83 | { | |
84 | struct ptr_ring *r = &pool->ring; | |
85 | struct page *page; | |
86 | ||
87 | /* Quicker fallback, avoid locks when ring is empty */ | |
88 | if (__ptr_ring_empty(r)) | |
89 | return NULL; | |
90 | ||
91 | /* Test for safe-context, caller should provide this guarantee */ | |
92 | if (likely(in_serving_softirq())) { | |
93 | if (likely(pool->alloc.count)) { | |
94 | /* Fast-path */ | |
95 | page = pool->alloc.cache[--pool->alloc.count]; | |
96 | return page; | |
97 | } | |
98 | /* Slower-path: Alloc array empty, time to refill | |
99 | * | |
100 | * Open-coded bulk ptr_ring consumer. | |
101 | * | |
102 | * Discussion: the ring consumer lock is not really | |
103 | * needed due to the softirq/NAPI protection, but | |
104 | * later need the ability to reclaim pages on the | |
105 | * ring. Thus, keeping the locks. | |
106 | */ | |
107 | spin_lock(&r->consumer_lock); | |
108 | while ((page = __ptr_ring_consume(r))) { | |
109 | if (pool->alloc.count == PP_ALLOC_CACHE_REFILL) | |
110 | break; | |
111 | pool->alloc.cache[pool->alloc.count++] = page; | |
112 | } | |
113 | spin_unlock(&r->consumer_lock); | |
114 | return page; | |
115 | } | |
116 | ||
117 | /* Slow-path: Get page from locked ring queue */ | |
118 | page = ptr_ring_consume(&pool->ring); | |
119 | return page; | |
120 | } | |
121 | ||
122 | /* slow path */ | |
123 | noinline | |
124 | static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool, | |
125 | gfp_t _gfp) | |
126 | { | |
127 | struct page *page; | |
128 | gfp_t gfp = _gfp; | |
129 | dma_addr_t dma; | |
130 | ||
131 | /* We could always set __GFP_COMP, and avoid this branch, as | |
132 | * prep_new_page() can handle order-0 with __GFP_COMP. | |
133 | */ | |
134 | if (pool->p.order) | |
135 | gfp |= __GFP_COMP; | |
136 | ||
137 | /* FUTURE development: | |
138 | * | |
139 | * Current slow-path essentially falls back to single page | |
140 | * allocations, which doesn't improve performance. This code | |
141 | * need bulk allocation support from the page allocator code. | |
142 | */ | |
143 | ||
144 | /* Cache was empty, do real allocation */ | |
145 | page = alloc_pages_node(pool->p.nid, gfp, pool->p.order); | |
146 | if (!page) | |
147 | return NULL; | |
148 | ||
149 | if (!(pool->p.flags & PP_FLAG_DMA_MAP)) | |
150 | goto skip_dma_map; | |
151 | ||
1567b85e IA |
152 | /* Setup DMA mapping: use 'struct page' area for storing DMA-addr |
153 | * since dma_addr_t can be either 32 or 64 bits and does not always fit | |
154 | * into page private data (i.e 32bit cpu with 64bit DMA caps) | |
ff7d6b27 JDB |
155 | * This mapping is kept for lifetime of page, until leaving pool. |
156 | */ | |
13f16d9d JDB |
157 | dma = dma_map_page_attrs(pool->p.dev, page, 0, |
158 | (PAGE_SIZE << pool->p.order), | |
159 | pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); | |
ff7d6b27 JDB |
160 | if (dma_mapping_error(pool->p.dev, dma)) { |
161 | put_page(page); | |
162 | return NULL; | |
163 | } | |
1567b85e | 164 | page->dma_addr = dma; |
ff7d6b27 JDB |
165 | |
166 | skip_dma_map: | |
99c07c43 JDB |
167 | /* Track how many pages are held 'in-flight' */ |
168 | pool->pages_state_hold_cnt++; | |
169 | ||
32c28f7e JDB |
170 | trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt); |
171 | ||
ff7d6b27 JDB |
172 | /* When page just alloc'ed is should/must have refcnt 1. */ |
173 | return page; | |
174 | } | |
175 | ||
176 | /* For using page_pool replace: alloc_pages() API calls, but provide | |
177 | * synchronization guarantee for allocation side. | |
178 | */ | |
179 | struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp) | |
180 | { | |
181 | struct page *page; | |
182 | ||
183 | /* Fast-path: Get a page from cache */ | |
184 | page = __page_pool_get_cached(pool); | |
185 | if (page) | |
186 | return page; | |
187 | ||
188 | /* Slow-path: cache empty, do real allocation */ | |
189 | page = __page_pool_alloc_pages_slow(pool, gfp); | |
190 | return page; | |
191 | } | |
192 | EXPORT_SYMBOL(page_pool_alloc_pages); | |
193 | ||
99c07c43 JDB |
194 | /* Calculate distance between two u32 values, valid if distance is below 2^(31) |
195 | * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution | |
196 | */ | |
197 | #define _distance(a, b) (s32)((a) - (b)) | |
198 | ||
199 | static s32 page_pool_inflight(struct page_pool *pool) | |
200 | { | |
201 | u32 release_cnt = atomic_read(&pool->pages_state_release_cnt); | |
202 | u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt); | |
203 | s32 distance; | |
204 | ||
205 | distance = _distance(hold_cnt, release_cnt); | |
206 | ||
32c28f7e | 207 | trace_page_pool_inflight(pool, distance, hold_cnt, release_cnt); |
99c07c43 JDB |
208 | return distance; |
209 | } | |
210 | ||
211 | static bool __page_pool_safe_to_destroy(struct page_pool *pool) | |
212 | { | |
213 | s32 inflight = page_pool_inflight(pool); | |
214 | ||
215 | /* The distance should not be able to become negative */ | |
216 | WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight); | |
217 | ||
218 | return (inflight == 0); | |
219 | } | |
220 | ||
ff7d6b27 JDB |
221 | /* Cleanup page_pool state from page */ |
222 | static void __page_pool_clean_page(struct page_pool *pool, | |
223 | struct page *page) | |
224 | { | |
1567b85e IA |
225 | dma_addr_t dma; |
226 | ||
ff7d6b27 | 227 | if (!(pool->p.flags & PP_FLAG_DMA_MAP)) |
99c07c43 | 228 | goto skip_dma_unmap; |
ff7d6b27 | 229 | |
1567b85e | 230 | dma = page->dma_addr; |
ff7d6b27 | 231 | /* DMA unmap */ |
13f16d9d JDB |
232 | dma_unmap_page_attrs(pool->p.dev, dma, |
233 | PAGE_SIZE << pool->p.order, pool->p.dma_dir, | |
234 | DMA_ATTR_SKIP_CPU_SYNC); | |
1567b85e | 235 | page->dma_addr = 0; |
99c07c43 JDB |
236 | skip_dma_unmap: |
237 | atomic_inc(&pool->pages_state_release_cnt); | |
32c28f7e JDB |
238 | trace_page_pool_state_release(pool, page, |
239 | atomic_read(&pool->pages_state_release_cnt)); | |
ff7d6b27 JDB |
240 | } |
241 | ||
a25d50bf IA |
242 | /* unmap the page and clean our state */ |
243 | void page_pool_unmap_page(struct page_pool *pool, struct page *page) | |
244 | { | |
99c07c43 JDB |
245 | /* When page is unmapped, this implies page will not be |
246 | * returned to page_pool. | |
247 | */ | |
a25d50bf IA |
248 | __page_pool_clean_page(pool, page); |
249 | } | |
250 | EXPORT_SYMBOL(page_pool_unmap_page); | |
251 | ||
ff7d6b27 JDB |
252 | /* Return a page to the page allocator, cleaning up our state */ |
253 | static void __page_pool_return_page(struct page_pool *pool, struct page *page) | |
254 | { | |
255 | __page_pool_clean_page(pool, page); | |
99c07c43 | 256 | |
ff7d6b27 JDB |
257 | put_page(page); |
258 | /* An optimization would be to call __free_pages(page, pool->p.order) | |
259 | * knowing page is not part of page-cache (thus avoiding a | |
260 | * __page_cache_release() call). | |
261 | */ | |
262 | } | |
263 | ||
264 | static bool __page_pool_recycle_into_ring(struct page_pool *pool, | |
265 | struct page *page) | |
266 | { | |
267 | int ret; | |
268 | /* BH protection not needed if current is serving softirq */ | |
269 | if (in_serving_softirq()) | |
270 | ret = ptr_ring_produce(&pool->ring, page); | |
271 | else | |
272 | ret = ptr_ring_produce_bh(&pool->ring, page); | |
273 | ||
274 | return (ret == 0) ? true : false; | |
275 | } | |
276 | ||
277 | /* Only allow direct recycling in special circumstances, into the | |
278 | * alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case. | |
279 | * | |
280 | * Caller must provide appropriate safe context. | |
281 | */ | |
282 | static bool __page_pool_recycle_direct(struct page *page, | |
283 | struct page_pool *pool) | |
284 | { | |
285 | if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) | |
286 | return false; | |
287 | ||
288 | /* Caller MUST have verified/know (page_ref_count(page) == 1) */ | |
289 | pool->alloc.cache[pool->alloc.count++] = page; | |
290 | return true; | |
291 | } | |
292 | ||
293 | void __page_pool_put_page(struct page_pool *pool, | |
294 | struct page *page, bool allow_direct) | |
295 | { | |
296 | /* This allocator is optimized for the XDP mode that uses | |
297 | * one-frame-per-page, but have fallbacks that act like the | |
298 | * regular page allocator APIs. | |
299 | * | |
300 | * refcnt == 1 means page_pool owns page, and can recycle it. | |
301 | */ | |
302 | if (likely(page_ref_count(page) == 1)) { | |
303 | /* Read barrier done in page_ref_count / READ_ONCE */ | |
304 | ||
305 | if (allow_direct && in_serving_softirq()) | |
306 | if (__page_pool_recycle_direct(page, pool)) | |
307 | return; | |
308 | ||
309 | if (!__page_pool_recycle_into_ring(pool, page)) { | |
310 | /* Cache full, fallback to free pages */ | |
311 | __page_pool_return_page(pool, page); | |
312 | } | |
313 | return; | |
314 | } | |
315 | /* Fallback/non-XDP mode: API user have elevated refcnt. | |
316 | * | |
317 | * Many drivers split up the page into fragments, and some | |
318 | * want to keep doing this to save memory and do refcnt based | |
319 | * recycling. Support this use case too, to ease drivers | |
320 | * switching between XDP/non-XDP. | |
321 | * | |
322 | * In-case page_pool maintains the DMA mapping, API user must | |
323 | * call page_pool_put_page once. In this elevated refcnt | |
324 | * case, the DMA is unmapped/released, as driver is likely | |
325 | * doing refcnt based recycle tricks, meaning another process | |
326 | * will be invoking put_page. | |
327 | */ | |
328 | __page_pool_clean_page(pool, page); | |
329 | put_page(page); | |
330 | } | |
331 | EXPORT_SYMBOL(__page_pool_put_page); | |
332 | ||
333 | static void __page_pool_empty_ring(struct page_pool *pool) | |
334 | { | |
335 | struct page *page; | |
336 | ||
337 | /* Empty recycle ring */ | |
4905bd9a | 338 | while ((page = ptr_ring_consume_bh(&pool->ring))) { |
ff7d6b27 JDB |
339 | /* Verify the refcnt invariant of cached pages */ |
340 | if (!(page_ref_count(page) == 1)) | |
341 | pr_crit("%s() page_pool refcnt %d violation\n", | |
342 | __func__, page_ref_count(page)); | |
343 | ||
344 | __page_pool_return_page(pool, page); | |
345 | } | |
346 | } | |
347 | ||
d956a048 JDB |
348 | static void __warn_in_flight(struct page_pool *pool) |
349 | { | |
350 | u32 release_cnt = atomic_read(&pool->pages_state_release_cnt); | |
351 | u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt); | |
352 | s32 distance; | |
353 | ||
354 | distance = _distance(hold_cnt, release_cnt); | |
355 | ||
356 | /* Drivers should fix this, but only problematic when DMA is used */ | |
357 | WARN(1, "Still in-flight pages:%d hold:%u released:%u", | |
358 | distance, hold_cnt, release_cnt); | |
359 | } | |
360 | ||
e54cfd7e JDB |
361 | void __page_pool_free(struct page_pool *pool) |
362 | { | |
1da4bbef IK |
363 | /* Only last user actually free/release resources */ |
364 | if (!page_pool_put(pool)) | |
365 | return; | |
366 | ||
e54cfd7e JDB |
367 | WARN(pool->alloc.count, "API usage violation"); |
368 | WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty"); | |
d956a048 JDB |
369 | |
370 | /* Can happen due to forced shutdown */ | |
371 | if (!__page_pool_safe_to_destroy(pool)) | |
372 | __warn_in_flight(pool); | |
e54cfd7e JDB |
373 | |
374 | ptr_ring_cleanup(&pool->ring, NULL); | |
f71fec47 JDB |
375 | |
376 | if (pool->p.flags & PP_FLAG_DMA_MAP) | |
377 | put_device(pool->p.dev); | |
378 | ||
e54cfd7e JDB |
379 | kfree(pool); |
380 | } | |
381 | EXPORT_SYMBOL(__page_pool_free); | |
382 | ||
99c07c43 JDB |
383 | /* Request to shutdown: release pages cached by page_pool, and check |
384 | * for in-flight pages | |
385 | */ | |
386 | bool __page_pool_request_shutdown(struct page_pool *pool) | |
ff7d6b27 JDB |
387 | { |
388 | struct page *page; | |
389 | ||
390 | /* Empty alloc cache, assume caller made sure this is | |
391 | * no-longer in use, and page_pool_alloc_pages() cannot be | |
392 | * call concurrently. | |
393 | */ | |
394 | while (pool->alloc.count) { | |
395 | page = pool->alloc.cache[--pool->alloc.count]; | |
396 | __page_pool_return_page(pool, page); | |
397 | } | |
398 | ||
399 | /* No more consumers should exist, but producers could still | |
400 | * be in-flight. | |
401 | */ | |
402 | __page_pool_empty_ring(pool); | |
403 | ||
99c07c43 | 404 | return __page_pool_safe_to_destroy(pool); |
ff7d6b27 | 405 | } |
99c07c43 | 406 | EXPORT_SYMBOL(__page_pool_request_shutdown); |