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