linux/net/core/page_pool.c
Liang Chen aaf153aece page_pool: halve BIAS_MAX for multiple user references of a fragment
Up to now, we were only subtracting from the number of used page fragments
to figure out when a page could be freed or recycled. A following patch
introduces support for multiple users referencing the same fragment. So
reduce the initial page fragments value to half to avoid overflowing.

Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Mina Almasry <almarsymina@google.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-12-17 10:56:33 +00:00

990 lines
26 KiB
C

/* SPDX-License-Identifier: GPL-2.0
*
* page_pool.c
* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
* Copyright (C) 2016 Red Hat, Inc.
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <net/page_pool/helpers.h>
#include <net/xdp.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/page-flags.h>
#include <linux/mm.h> /* for put_page() */
#include <linux/poison.h>
#include <linux/ethtool.h>
#include <linux/netdevice.h>
#include <trace/events/page_pool.h>
#include "page_pool_priv.h"
#define DEFER_TIME (msecs_to_jiffies(1000))
#define DEFER_WARN_INTERVAL (60 * HZ)
#define BIAS_MAX (LONG_MAX >> 1)
#ifdef CONFIG_PAGE_POOL_STATS
/* alloc_stat_inc is intended to be used in softirq context */
#define alloc_stat_inc(pool, __stat) (pool->alloc_stats.__stat++)
/* recycle_stat_inc is safe to use when preemption is possible. */
#define recycle_stat_inc(pool, __stat) \
do { \
struct page_pool_recycle_stats __percpu *s = pool->recycle_stats; \
this_cpu_inc(s->__stat); \
} while (0)
#define recycle_stat_add(pool, __stat, val) \
do { \
struct page_pool_recycle_stats __percpu *s = pool->recycle_stats; \
this_cpu_add(s->__stat, val); \
} while (0)
static const char pp_stats[][ETH_GSTRING_LEN] = {
"rx_pp_alloc_fast",
"rx_pp_alloc_slow",
"rx_pp_alloc_slow_ho",
"rx_pp_alloc_empty",
"rx_pp_alloc_refill",
"rx_pp_alloc_waive",
"rx_pp_recycle_cached",
"rx_pp_recycle_cache_full",
"rx_pp_recycle_ring",
"rx_pp_recycle_ring_full",
"rx_pp_recycle_released_ref",
};
/**
* page_pool_get_stats() - fetch page pool stats
* @pool: pool from which page was allocated
* @stats: struct page_pool_stats to fill in
*
* Retrieve statistics about the page_pool. This API is only available
* if the kernel has been configured with ``CONFIG_PAGE_POOL_STATS=y``.
* A pointer to a caller allocated struct page_pool_stats structure
* is passed to this API which is filled in. The caller can then report
* those stats to the user (perhaps via ethtool, debugfs, etc.).
*/
bool page_pool_get_stats(const struct page_pool *pool,
struct page_pool_stats *stats)
{
int cpu = 0;
if (!stats)
return false;
/* The caller is responsible to initialize stats. */
stats->alloc_stats.fast += pool->alloc_stats.fast;
stats->alloc_stats.slow += pool->alloc_stats.slow;
stats->alloc_stats.slow_high_order += pool->alloc_stats.slow_high_order;
stats->alloc_stats.empty += pool->alloc_stats.empty;
stats->alloc_stats.refill += pool->alloc_stats.refill;
stats->alloc_stats.waive += pool->alloc_stats.waive;
for_each_possible_cpu(cpu) {
const struct page_pool_recycle_stats *pcpu =
per_cpu_ptr(pool->recycle_stats, cpu);
stats->recycle_stats.cached += pcpu->cached;
stats->recycle_stats.cache_full += pcpu->cache_full;
stats->recycle_stats.ring += pcpu->ring;
stats->recycle_stats.ring_full += pcpu->ring_full;
stats->recycle_stats.released_refcnt += pcpu->released_refcnt;
}
return true;
}
EXPORT_SYMBOL(page_pool_get_stats);
u8 *page_pool_ethtool_stats_get_strings(u8 *data)
{
int i;
for (i = 0; i < ARRAY_SIZE(pp_stats); i++) {
memcpy(data, pp_stats[i], ETH_GSTRING_LEN);
data += ETH_GSTRING_LEN;
}
return data;
}
EXPORT_SYMBOL(page_pool_ethtool_stats_get_strings);
int page_pool_ethtool_stats_get_count(void)
{
return ARRAY_SIZE(pp_stats);
}
EXPORT_SYMBOL(page_pool_ethtool_stats_get_count);
u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
{
struct page_pool_stats *pool_stats = stats;
*data++ = pool_stats->alloc_stats.fast;
*data++ = pool_stats->alloc_stats.slow;
*data++ = pool_stats->alloc_stats.slow_high_order;
*data++ = pool_stats->alloc_stats.empty;
*data++ = pool_stats->alloc_stats.refill;
*data++ = pool_stats->alloc_stats.waive;
*data++ = pool_stats->recycle_stats.cached;
*data++ = pool_stats->recycle_stats.cache_full;
*data++ = pool_stats->recycle_stats.ring;
*data++ = pool_stats->recycle_stats.ring_full;
*data++ = pool_stats->recycle_stats.released_refcnt;
return data;
}
EXPORT_SYMBOL(page_pool_ethtool_stats_get);
#else
#define alloc_stat_inc(pool, __stat)
#define recycle_stat_inc(pool, __stat)
#define recycle_stat_add(pool, __stat, val)
#endif
static bool page_pool_producer_lock(struct page_pool *pool)
__acquires(&pool->ring.producer_lock)
{
bool in_softirq = in_softirq();
if (in_softirq)
spin_lock(&pool->ring.producer_lock);
else
spin_lock_bh(&pool->ring.producer_lock);
return in_softirq;
}
static void page_pool_producer_unlock(struct page_pool *pool,
bool in_softirq)
__releases(&pool->ring.producer_lock)
{
if (in_softirq)
spin_unlock(&pool->ring.producer_lock);
else
spin_unlock_bh(&pool->ring.producer_lock);
}
static int page_pool_init(struct page_pool *pool,
const struct page_pool_params *params)
{
unsigned int ring_qsize = 1024; /* Default */
memcpy(&pool->p, &params->fast, sizeof(pool->p));
memcpy(&pool->slow, &params->slow, sizeof(pool->slow));
/* Validate only known flags were used */
if (pool->p.flags & ~(PP_FLAG_ALL))
return -EINVAL;
if (pool->p.pool_size)
ring_qsize = pool->p.pool_size;
/* Sanity limit mem that can be pinned down */
if (ring_qsize > 32768)
return -E2BIG;
/* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
* DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
* which is the XDP_TX use-case.
*/
if (pool->p.flags & PP_FLAG_DMA_MAP) {
if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
(pool->p.dma_dir != DMA_BIDIRECTIONAL))
return -EINVAL;
}
if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
/* In order to request DMA-sync-for-device the page
* needs to be mapped
*/
if (!(pool->p.flags & PP_FLAG_DMA_MAP))
return -EINVAL;
if (!pool->p.max_len)
return -EINVAL;
/* pool->p.offset has to be set according to the address
* offset used by the DMA engine to start copying rx data
*/
}
pool->has_init_callback = !!pool->slow.init_callback;
#ifdef CONFIG_PAGE_POOL_STATS
pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats);
if (!pool->recycle_stats)
return -ENOMEM;
#endif
if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0) {
#ifdef CONFIG_PAGE_POOL_STATS
free_percpu(pool->recycle_stats);
#endif
return -ENOMEM;
}
atomic_set(&pool->pages_state_release_cnt, 0);
/* Driver calling page_pool_create() also call page_pool_destroy() */
refcount_set(&pool->user_cnt, 1);
if (pool->p.flags & PP_FLAG_DMA_MAP)
get_device(pool->p.dev);
return 0;
}
static void page_pool_uninit(struct page_pool *pool)
{
ptr_ring_cleanup(&pool->ring, NULL);
if (pool->p.flags & PP_FLAG_DMA_MAP)
put_device(pool->p.dev);
#ifdef CONFIG_PAGE_POOL_STATS
free_percpu(pool->recycle_stats);
#endif
}
/**
* page_pool_create() - create a page pool.
* @params: parameters, see struct page_pool_params
*/
struct page_pool *page_pool_create(const struct page_pool_params *params)
{
struct page_pool *pool;
int err;
pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid);
if (!pool)
return ERR_PTR(-ENOMEM);
err = page_pool_init(pool, params);
if (err < 0)
goto err_free;
err = page_pool_list(pool);
if (err)
goto err_uninit;
return pool;
err_uninit:
page_pool_uninit(pool);
err_free:
pr_warn("%s() gave up with errno %d\n", __func__, err);
kfree(pool);
return ERR_PTR(err);
}
EXPORT_SYMBOL(page_pool_create);
static void page_pool_return_page(struct page_pool *pool, struct page *page);
noinline
static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
{
struct ptr_ring *r = &pool->ring;
struct page *page;
int pref_nid; /* preferred NUMA node */
/* Quicker fallback, avoid locks when ring is empty */
if (__ptr_ring_empty(r)) {
alloc_stat_inc(pool, empty);
return NULL;
}
/* Softirq guarantee CPU and thus NUMA node is stable. This,
* assumes CPU refilling driver RX-ring will also run RX-NAPI.
*/
#ifdef CONFIG_NUMA
pref_nid = (pool->p.nid == NUMA_NO_NODE) ? numa_mem_id() : pool->p.nid;
#else
/* Ignore pool->p.nid setting if !CONFIG_NUMA, helps compiler */
pref_nid = numa_mem_id(); /* will be zero like page_to_nid() */
#endif
/* Refill alloc array, but only if NUMA match */
do {
page = __ptr_ring_consume(r);
if (unlikely(!page))
break;
if (likely(page_to_nid(page) == pref_nid)) {
pool->alloc.cache[pool->alloc.count++] = page;
} else {
/* NUMA mismatch;
* (1) release 1 page to page-allocator and
* (2) break out to fallthrough to alloc_pages_node.
* This limit stress on page buddy alloactor.
*/
page_pool_return_page(pool, page);
alloc_stat_inc(pool, waive);
page = NULL;
break;
}
} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
/* Return last page */
if (likely(pool->alloc.count > 0)) {
page = pool->alloc.cache[--pool->alloc.count];
alloc_stat_inc(pool, refill);
}
return page;
}
/* fast path */
static struct page *__page_pool_get_cached(struct page_pool *pool)
{
struct page *page;
/* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
if (likely(pool->alloc.count)) {
/* Fast-path */
page = pool->alloc.cache[--pool->alloc.count];
alloc_stat_inc(pool, fast);
} else {
page = page_pool_refill_alloc_cache(pool);
}
return page;
}
static void page_pool_dma_sync_for_device(struct page_pool *pool,
struct page *page,
unsigned int dma_sync_size)
{
dma_addr_t dma_addr = page_pool_get_dma_addr(page);
dma_sync_size = min(dma_sync_size, pool->p.max_len);
dma_sync_single_range_for_device(pool->p.dev, dma_addr,
pool->p.offset, dma_sync_size,
pool->p.dma_dir);
}
static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
{
dma_addr_t dma;
/* Setup DMA mapping: use 'struct page' area for storing DMA-addr
* since dma_addr_t can be either 32 or 64 bits and does not always fit
* into page private data (i.e 32bit cpu with 64bit DMA caps)
* This mapping is kept for lifetime of page, until leaving pool.
*/
dma = dma_map_page_attrs(pool->p.dev, page, 0,
(PAGE_SIZE << pool->p.order),
pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC |
DMA_ATTR_WEAK_ORDERING);
if (dma_mapping_error(pool->p.dev, dma))
return false;
if (page_pool_set_dma_addr(page, dma))
goto unmap_failed;
if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
return true;
unmap_failed:
WARN_ON_ONCE("unexpected DMA address, please report to netdev@");
dma_unmap_page_attrs(pool->p.dev, dma,
PAGE_SIZE << pool->p.order, pool->p.dma_dir,
DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
return false;
}
static void page_pool_set_pp_info(struct page_pool *pool,
struct page *page)
{
page->pp = pool;
page->pp_magic |= PP_SIGNATURE;
/* Ensuring all pages have been split into one fragment initially:
* page_pool_set_pp_info() is only called once for every page when it
* is allocated from the page allocator and page_pool_fragment_page()
* is dirtying the same cache line as the page->pp_magic above, so
* the overhead is negligible.
*/
page_pool_fragment_page(page, 1);
if (pool->has_init_callback)
pool->slow.init_callback(page, pool->slow.init_arg);
}
static void page_pool_clear_pp_info(struct page *page)
{
page->pp_magic = 0;
page->pp = NULL;
}
static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
gfp_t gfp)
{
struct page *page;
gfp |= __GFP_COMP;
page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
if (unlikely(!page))
return NULL;
if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
unlikely(!page_pool_dma_map(pool, page))) {
put_page(page);
return NULL;
}
alloc_stat_inc(pool, slow_high_order);
page_pool_set_pp_info(pool, page);
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
return page;
}
/* slow path */
noinline
static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
gfp_t gfp)
{
const int bulk = PP_ALLOC_CACHE_REFILL;
unsigned int pp_flags = pool->p.flags;
unsigned int pp_order = pool->p.order;
struct page *page;
int i, nr_pages;
/* Don't support bulk alloc for high-order pages */
if (unlikely(pp_order))
return __page_pool_alloc_page_order(pool, gfp);
/* Unnecessary as alloc cache is empty, but guarantees zero count */
if (unlikely(pool->alloc.count > 0))
return pool->alloc.cache[--pool->alloc.count];
/* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
nr_pages = alloc_pages_bulk_array_node(gfp, pool->p.nid, bulk,
pool->alloc.cache);
if (unlikely(!nr_pages))
return NULL;
/* Pages have been filled into alloc.cache array, but count is zero and
* page element have not been (possibly) DMA mapped.
*/
for (i = 0; i < nr_pages; i++) {
page = pool->alloc.cache[i];
if ((pp_flags & PP_FLAG_DMA_MAP) &&
unlikely(!page_pool_dma_map(pool, page))) {
put_page(page);
continue;
}
page_pool_set_pp_info(pool, page);
pool->alloc.cache[pool->alloc.count++] = page;
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
trace_page_pool_state_hold(pool, page,
pool->pages_state_hold_cnt);
}
/* Return last page */
if (likely(pool->alloc.count > 0)) {
page = pool->alloc.cache[--pool->alloc.count];
alloc_stat_inc(pool, slow);
} else {
page = NULL;
}
/* When page just alloc'ed is should/must have refcnt 1. */
return page;
}
/* For using page_pool replace: alloc_pages() API calls, but provide
* synchronization guarantee for allocation side.
*/
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
{
struct page *page;
/* Fast-path: Get a page from cache */
page = __page_pool_get_cached(pool);
if (page)
return page;
/* Slow-path: cache empty, do real allocation */
page = __page_pool_alloc_pages_slow(pool, gfp);
return page;
}
EXPORT_SYMBOL(page_pool_alloc_pages);
/* Calculate distance between two u32 values, valid if distance is below 2^(31)
* https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
*/
#define _distance(a, b) (s32)((a) - (b))
s32 page_pool_inflight(const struct page_pool *pool, bool strict)
{
u32 release_cnt = atomic_read(&pool->pages_state_release_cnt);
u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt);
s32 inflight;
inflight = _distance(hold_cnt, release_cnt);
if (strict) {
trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);
WARN(inflight < 0, "Negative(%d) inflight packet-pages",
inflight);
} else {
inflight = max(0, inflight);
}
return inflight;
}
static __always_inline
void __page_pool_release_page_dma(struct page_pool *pool, struct page *page)
{
dma_addr_t dma;
if (!(pool->p.flags & PP_FLAG_DMA_MAP))
/* Always account for inflight pages, even if we didn't
* map them
*/
return;
dma = page_pool_get_dma_addr(page);
/* When page is unmapped, it cannot be returned to our pool */
dma_unmap_page_attrs(pool->p.dev, dma,
PAGE_SIZE << pool->p.order, pool->p.dma_dir,
DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
page_pool_set_dma_addr(page, 0);
}
/* Disconnects a page (from a page_pool). API users can have a need
* to disconnect a page (from a page_pool), to allow it to be used as
* a regular page (that will eventually be returned to the normal
* page-allocator via put_page).
*/
void page_pool_return_page(struct page_pool *pool, struct page *page)
{
int count;
__page_pool_release_page_dma(pool, page);
page_pool_clear_pp_info(page);
/* This may be the last page returned, releasing the pool, so
* it is not safe to reference pool afterwards.
*/
count = atomic_inc_return_relaxed(&pool->pages_state_release_cnt);
trace_page_pool_state_release(pool, page, count);
put_page(page);
/* An optimization would be to call __free_pages(page, pool->p.order)
* knowing page is not part of page-cache (thus avoiding a
* __page_cache_release() call).
*/
}
static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
{
int ret;
/* BH protection not needed if current is softirq */
if (in_softirq())
ret = ptr_ring_produce(&pool->ring, page);
else
ret = ptr_ring_produce_bh(&pool->ring, page);
if (!ret) {
recycle_stat_inc(pool, ring);
return true;
}
return false;
}
/* Only allow direct recycling in special circumstances, into the
* alloc side cache. E.g. during RX-NAPI processing for XDP_DROP use-case.
*
* Caller must provide appropriate safe context.
*/
static bool page_pool_recycle_in_cache(struct page *page,
struct page_pool *pool)
{
if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) {
recycle_stat_inc(pool, cache_full);
return false;
}
/* Caller MUST have verified/know (page_ref_count(page) == 1) */
pool->alloc.cache[pool->alloc.count++] = page;
recycle_stat_inc(pool, cached);
return true;
}
/* If the page refcnt == 1, this will try to recycle the page.
* if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
* the configured size min(dma_sync_size, pool->max_len).
* If the page refcnt != 1, then the page will be returned to memory
* subsystem.
*/
static __always_inline struct page *
__page_pool_put_page(struct page_pool *pool, struct page *page,
unsigned int dma_sync_size, bool allow_direct)
{
lockdep_assert_no_hardirq();
/* This allocator is optimized for the XDP mode that uses
* one-frame-per-page, but have fallbacks that act like the
* regular page allocator APIs.
*
* refcnt == 1 means page_pool owns page, and can recycle it.
*
* page is NOT reusable when allocated when system is under
* some pressure. (page_is_pfmemalloc)
*/
if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
/* Read barrier done in page_ref_count / READ_ONCE */
if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
page_pool_dma_sync_for_device(pool, page,
dma_sync_size);
if (allow_direct && in_softirq() &&
page_pool_recycle_in_cache(page, pool))
return NULL;
/* Page found as candidate for recycling */
return page;
}
/* Fallback/non-XDP mode: API user have elevated refcnt.
*
* Many drivers split up the page into fragments, and some
* want to keep doing this to save memory and do refcnt based
* recycling. Support this use case too, to ease drivers
* switching between XDP/non-XDP.
*
* In-case page_pool maintains the DMA mapping, API user must
* call page_pool_put_page once. In this elevated refcnt
* case, the DMA is unmapped/released, as driver is likely
* doing refcnt based recycle tricks, meaning another process
* will be invoking put_page.
*/
recycle_stat_inc(pool, released_refcnt);
page_pool_return_page(pool, page);
return NULL;
}
void page_pool_put_unrefed_page(struct page_pool *pool, struct page *page,
unsigned int dma_sync_size, bool allow_direct)
{
page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
if (page && !page_pool_recycle_in_ring(pool, page)) {
/* Cache full, fallback to free pages */
recycle_stat_inc(pool, ring_full);
page_pool_return_page(pool, page);
}
}
EXPORT_SYMBOL(page_pool_put_unrefed_page);
/**
* page_pool_put_page_bulk() - release references on multiple pages
* @pool: pool from which pages were allocated
* @data: array holding page pointers
* @count: number of pages in @data
*
* Tries to refill a number of pages into the ptr_ring cache holding ptr_ring
* producer lock. If the ptr_ring is full, page_pool_put_page_bulk()
* will release leftover pages to the page allocator.
* page_pool_put_page_bulk() is suitable to be run inside the driver NAPI tx
* completion loop for the XDP_REDIRECT use case.
*
* Please note the caller must not use data area after running
* page_pool_put_page_bulk(), as this function overwrites it.
*/
void page_pool_put_page_bulk(struct page_pool *pool, void **data,
int count)
{
int i, bulk_len = 0;
bool in_softirq;
for (i = 0; i < count; i++) {
struct page *page = virt_to_head_page(data[i]);
/* It is not the last user for the page frag case */
if (!page_pool_is_last_ref(page))
continue;
page = __page_pool_put_page(pool, page, -1, false);
/* Approved for bulk recycling in ptr_ring cache */
if (page)
data[bulk_len++] = page;
}
if (unlikely(!bulk_len))
return;
/* Bulk producer into ptr_ring page_pool cache */
in_softirq = page_pool_producer_lock(pool);
for (i = 0; i < bulk_len; i++) {
if (__ptr_ring_produce(&pool->ring, data[i])) {
/* ring full */
recycle_stat_inc(pool, ring_full);
break;
}
}
recycle_stat_add(pool, ring, i);
page_pool_producer_unlock(pool, in_softirq);
/* Hopefully all pages was return into ptr_ring */
if (likely(i == bulk_len))
return;
/* ptr_ring cache full, free remaining pages outside producer lock
* since put_page() with refcnt == 1 can be an expensive operation
*/
for (; i < bulk_len; i++)
page_pool_return_page(pool, data[i]);
}
EXPORT_SYMBOL(page_pool_put_page_bulk);
static struct page *page_pool_drain_frag(struct page_pool *pool,
struct page *page)
{
long drain_count = BIAS_MAX - pool->frag_users;
/* Some user is still using the page frag */
if (likely(page_pool_unref_page(page, drain_count)))
return NULL;
if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
page_pool_dma_sync_for_device(pool, page, -1);
return page;
}
page_pool_return_page(pool, page);
return NULL;
}
static void page_pool_free_frag(struct page_pool *pool)
{
long drain_count = BIAS_MAX - pool->frag_users;
struct page *page = pool->frag_page;
pool->frag_page = NULL;
if (!page || page_pool_unref_page(page, drain_count))
return;
page_pool_return_page(pool, page);
}
struct page *page_pool_alloc_frag(struct page_pool *pool,
unsigned int *offset,
unsigned int size, gfp_t gfp)
{
unsigned int max_size = PAGE_SIZE << pool->p.order;
struct page *page = pool->frag_page;
if (WARN_ON(size > max_size))
return NULL;
size = ALIGN(size, dma_get_cache_alignment());
*offset = pool->frag_offset;
if (page && *offset + size > max_size) {
page = page_pool_drain_frag(pool, page);
if (page) {
alloc_stat_inc(pool, fast);
goto frag_reset;
}
}
if (!page) {
page = page_pool_alloc_pages(pool, gfp);
if (unlikely(!page)) {
pool->frag_page = NULL;
return NULL;
}
pool->frag_page = page;
frag_reset:
pool->frag_users = 1;
*offset = 0;
pool->frag_offset = size;
page_pool_fragment_page(page, BIAS_MAX);
return page;
}
pool->frag_users++;
pool->frag_offset = *offset + size;
alloc_stat_inc(pool, fast);
return page;
}
EXPORT_SYMBOL(page_pool_alloc_frag);
static void page_pool_empty_ring(struct page_pool *pool)
{
struct page *page;
/* Empty recycle ring */
while ((page = ptr_ring_consume_bh(&pool->ring))) {
/* Verify the refcnt invariant of cached pages */
if (!(page_ref_count(page) == 1))
pr_crit("%s() page_pool refcnt %d violation\n",
__func__, page_ref_count(page));
page_pool_return_page(pool, page);
}
}
static void __page_pool_destroy(struct page_pool *pool)
{
if (pool->disconnect)
pool->disconnect(pool);
page_pool_unlist(pool);
page_pool_uninit(pool);
kfree(pool);
}
static void page_pool_empty_alloc_cache_once(struct page_pool *pool)
{
struct page *page;
if (pool->destroy_cnt)
return;
/* Empty alloc cache, assume caller made sure this is
* no-longer in use, and page_pool_alloc_pages() cannot be
* call concurrently.
*/
while (pool->alloc.count) {
page = pool->alloc.cache[--pool->alloc.count];
page_pool_return_page(pool, page);
}
}
static void page_pool_scrub(struct page_pool *pool)
{
page_pool_empty_alloc_cache_once(pool);
pool->destroy_cnt++;
/* No more consumers should exist, but producers could still
* be in-flight.
*/
page_pool_empty_ring(pool);
}
static int page_pool_release(struct page_pool *pool)
{
int inflight;
page_pool_scrub(pool);
inflight = page_pool_inflight(pool, true);
if (!inflight)
__page_pool_destroy(pool);
return inflight;
}
static void page_pool_release_retry(struct work_struct *wq)
{
struct delayed_work *dwq = to_delayed_work(wq);
struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw);
void *netdev;
int inflight;
inflight = page_pool_release(pool);
if (!inflight)
return;
/* Periodic warning for page pools the user can't see */
netdev = READ_ONCE(pool->slow.netdev);
if (time_after_eq(jiffies, pool->defer_warn) &&
(!netdev || netdev == NET_PTR_POISON)) {
int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;
pr_warn("%s() stalled pool shutdown: id %u, %d inflight %d sec\n",
__func__, pool->user.id, inflight, sec);
pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
}
/* Still not ready to be disconnected, retry later */
schedule_delayed_work(&pool->release_dw, DEFER_TIME);
}
void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
struct xdp_mem_info *mem)
{
refcount_inc(&pool->user_cnt);
pool->disconnect = disconnect;
pool->xdp_mem_id = mem->id;
}
void page_pool_unlink_napi(struct page_pool *pool)
{
if (!pool->p.napi)
return;
/* To avoid races with recycling and additional barriers make sure
* pool and NAPI are unlinked when NAPI is disabled.
*/
WARN_ON(!test_bit(NAPI_STATE_SCHED, &pool->p.napi->state) ||
READ_ONCE(pool->p.napi->list_owner) != -1);
WRITE_ONCE(pool->p.napi, NULL);
}
EXPORT_SYMBOL(page_pool_unlink_napi);
void page_pool_destroy(struct page_pool *pool)
{
if (!pool)
return;
if (!page_pool_put(pool))
return;
page_pool_unlink_napi(pool);
page_pool_free_frag(pool);
if (!page_pool_release(pool))
return;
page_pool_detached(pool);
pool->defer_start = jiffies;
pool->defer_warn = jiffies + DEFER_WARN_INTERVAL;
INIT_DELAYED_WORK(&pool->release_dw, page_pool_release_retry);
schedule_delayed_work(&pool->release_dw, DEFER_TIME);
}
EXPORT_SYMBOL(page_pool_destroy);
/* Caller must provide appropriate safe context, e.g. NAPI. */
void page_pool_update_nid(struct page_pool *pool, int new_nid)
{
struct page *page;
trace_page_pool_update_nid(pool, new_nid);
pool->p.nid = new_nid;
/* Flush pool alloc cache, as refill will check NUMA node */
while (pool->alloc.count) {
page = pool->alloc.cache[--pool->alloc.count];
page_pool_return_page(pool, page);
}
}
EXPORT_SYMBOL(page_pool_update_nid);