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/* SPDX-License-Identifier: GPL-2.0
*
* page_pool.h
* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
* Copyright (C) 2016 Red Hat, Inc.
*/
/**
* DOC: page_pool allocator
*
* This page_pool allocator is optimized for the XDP mode that
* uses one-frame-per-page, but have fallbacks that act like the
* regular page allocator APIs.
*
* Basic use involve replacing alloc_pages() calls with the
* page_pool_alloc_pages() call. Drivers should likely use
* page_pool_dev_alloc_pages() replacing dev_alloc_pages().
*
* API keeps track of in-flight pages, in-order to let API user know
* when it is safe to dealloactor page_pool object. Thus, API users
* must make sure to call page_pool_release_page() when a page is
* "leaving" the page_pool. Or call page_pool_put_page() where
* appropiate. For maintaining correct accounting.
*
* API user must only call page_pool_put_page() once on a page, as it
* will either recycle the page, or in case of elevated refcnt, it
* will release the DMA mapping and in-flight state accounting. We
* hope to lift this requirement in the future.
*/
#ifndef _NET_PAGE_POOL_H
#define _NET_PAGE_POOL_H
#include <linux/mm.h> /* Needed by ptr_ring */
#include <linux/ptr_ring.h>
#include <linux/dma-direction.h>
#define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA
* map/unmap
*/
#define PP_FLAG_DMA_SYNC_DEV BIT(1) /* If set all pages that the driver gets
* from page_pool will be
* DMA-synced-for-device according to
* the length provided by the device
* driver.
* Please note DMA-sync-for-CPU is still
* device driver responsibility
*/
#define PP_FLAG_PAGE_FRAG BIT(2) /* for page frag feature */
#define PP_FLAG_ALL (PP_FLAG_DMA_MAP |\
PP_FLAG_DMA_SYNC_DEV |\
PP_FLAG_PAGE_FRAG)
/*
* Fast allocation side cache array/stack
*
* The cache size and refill watermark is related to the network
* use-case. The NAPI budget is 64 packets. After a NAPI poll the RX
* ring is usually refilled and the max consumed elements will be 64,
* thus a natural max size of objects needed in the cache.
*
* Keeping room for more objects, is due to XDP_DROP use-case. As
* XDP_DROP allows the opportunity to recycle objects directly into
* this array, as it shares the same softirq/NAPI protection. If
* cache is already full (or partly full) then the XDP_DROP recycles
* would have to take a slower code path.
*/
#define PP_ALLOC_CACHE_SIZE 128
#define PP_ALLOC_CACHE_REFILL 64
struct pp_alloc_cache {
u32 count;
struct page *cache[PP_ALLOC_CACHE_SIZE];
};
struct page_pool_params {
unsigned int flags;
unsigned int order;
unsigned int pool_size;
int nid; /* Numa node id to allocate from pages from */
struct device *dev; /* device, for DMA pre-mapping purposes */
enum dma_data_direction dma_dir; /* DMA mapping direction */
unsigned int max_len; /* max DMA sync memory size */
unsigned int offset; /* DMA addr offset */
void (*init_callback)(struct page *page, void *arg);
void *init_arg;
};
#ifdef CONFIG_PAGE_POOL_STATS
struct page_pool_alloc_stats {
u64 fast; /* fast path allocations */
u64 slow; /* slow-path order 0 allocations */
u64 slow_high_order; /* slow-path high order allocations */
u64 empty; /* failed refills due to empty ptr ring, forcing
* slow path allocation
*/
u64 refill; /* allocations via successful refill */
u64 waive; /* failed refills due to numa zone mismatch */
};
struct page_pool_recycle_stats {
u64 cached; /* recycling placed page in the cache. */
u64 cache_full; /* cache was full */
u64 ring; /* recycling placed page back into ptr ring */
u64 ring_full; /* page was released from page-pool because
* PTR ring was full.
*/
u64 released_refcnt; /* page released because of elevated
* refcnt
*/
};
/* This struct wraps the above stats structs so users of the
* page_pool_get_stats API can pass a single argument when requesting the
* stats for the page pool.
*/
struct page_pool_stats {
struct page_pool_alloc_stats alloc_stats;
struct page_pool_recycle_stats recycle_stats;
};
int page_pool_ethtool_stats_get_count(void);
u8 *page_pool_ethtool_stats_get_strings(u8 *data);
u64 *page_pool_ethtool_stats_get(u64 *data, void *stats);
/*
* Drivers that wish to harvest page pool stats and report them to users
* (perhaps via ethtool, debugfs, or another mechanism) can allocate a
* struct page_pool_stats call page_pool_get_stats to get stats for the specified pool.
*/
bool page_pool_get_stats(struct page_pool *pool,
struct page_pool_stats *stats);
#else
static inline int page_pool_ethtool_stats_get_count(void)
{
return 0;
}
static inline u8 *page_pool_ethtool_stats_get_strings(u8 *data)
{
return data;
}
static inline u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
{
return data;
}
#endif
struct page_pool {
struct page_pool_params p;
struct delayed_work release_dw;
void (*disconnect)(void *);
unsigned long defer_start;
unsigned long defer_warn;
u32 pages_state_hold_cnt;
unsigned int frag_offset;
struct page *frag_page;
long frag_users;
#ifdef CONFIG_PAGE_POOL_STATS
/* these stats are incremented while in softirq context */
struct page_pool_alloc_stats alloc_stats;
#endif
u32 xdp_mem_id;
/*
* Data structure for allocation side
*
* Drivers allocation side usually already perform some kind
* of resource protection. Piggyback on this protection, and
* require driver to protect allocation side.
*
* For NIC drivers this means, allocate a page_pool per
* RX-queue. As the RX-queue is already protected by
* Softirq/BH scheduling and napi_schedule. NAPI schedule
* guarantee that a single napi_struct will only be scheduled
* on a single CPU (see napi_schedule).
*/
struct pp_alloc_cache alloc ____cacheline_aligned_in_smp;
/* Data structure for storing recycled pages.
*
* Returning/freeing pages is more complicated synchronization
* wise, because free's can happen on remote CPUs, with no
* association with allocation resource.
*
* Use ptr_ring, as it separates consumer and producer
* effeciently, it a way that doesn't bounce cache-lines.
*
* TODO: Implement bulk return pages into this structure.
*/
struct ptr_ring ring;
#ifdef CONFIG_PAGE_POOL_STATS
/* recycle stats are per-cpu to avoid locking */
struct page_pool_recycle_stats __percpu *recycle_stats;
#endif
atomic_t pages_state_release_cnt;
/* A page_pool is strictly tied to a single RX-queue being
* protected by NAPI, due to above pp_alloc_cache. This
* refcnt serves purpose is to simplify drivers error handling.
*/
refcount_t user_cnt;
u64 destroy_cnt;
};
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
{
gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
return page_pool_alloc_pages(pool, gfp);
}
struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
unsigned int size, gfp_t gfp);
static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
unsigned int *offset,
unsigned int size)
{
gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
return page_pool_alloc_frag(pool, offset, size, gfp);
}
/* get the stored dma direction. A driver might decide to treat this locally and
* avoid the extra cache line from page_pool to determine the direction
*/
static
inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
{
return pool->p.dma_dir;
}
bool page_pool_return_skb_page(struct page *page);
struct page_pool *page_pool_create(const struct page_pool_params *params);
struct xdp_mem_info;
#ifdef CONFIG_PAGE_POOL
void page_pool_destroy(struct page_pool *pool);
void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
struct xdp_mem_info *mem);
void page_pool_release_page(struct page_pool *pool, struct page *page);
void page_pool_put_page_bulk(struct page_pool *pool, void **data,
int count);
#else
static inline void page_pool_destroy(struct page_pool *pool)
{
}
static inline void page_pool_use_xdp_mem(struct page_pool *pool,
void (*disconnect)(void *),
struct xdp_mem_info *mem)
{
}
static inline void page_pool_release_page(struct page_pool *pool,
struct page *page)
{
}
static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
int count)
{
}
#endif
void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
unsigned int dma_sync_size,
bool allow_direct);
/* pp_frag_count represents the number of writers who can update the page
* either by updating skb->data or via DMA mappings for the device.
* We can't rely on the page refcnt for that as we don't know who might be
* holding page references and we can't reliably destroy or sync DMA mappings
* of the fragments.
*
* When pp_frag_count reaches 0 we can either recycle the page if the page
* refcnt is 1 or return it back to the memory allocator and destroy any
* mappings we have.
*/
static inline void page_pool_fragment_page(struct page *page, long nr)
{
atomic_long_set(&page->pp_frag_count, nr);
}
static inline long page_pool_defrag_page(struct page *page, long nr)
{
long ret;
/* If nr == pp_frag_count then we have cleared all remaining
* references to the page. No need to actually overwrite it, instead
* we can leave this to be overwritten by the calling function.
*
* The main advantage to doing this is that an atomic_read is
* generally a much cheaper operation than an atomic update,
* especially when dealing with a page that may be partitioned
* into only 2 or 3 pieces.
*/
if (atomic_long_read(&page->pp_frag_count) == nr)
return 0;
ret = atomic_long_sub_return(nr, &page->pp_frag_count);
WARN_ON(ret < 0);
return ret;
}
static inline bool page_pool_is_last_frag(struct page_pool *pool,
struct page *page)
{
/* If fragments aren't enabled or count is 0 we were the last user */
return !(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
(page_pool_defrag_page(page, 1) == 0);
}
static inline void page_pool_put_page(struct page_pool *pool,
struct page *page,
unsigned int dma_sync_size,
bool allow_direct)
{
/* When page_pool isn't compiled-in, net/core/xdp.c doesn't
* allow registering MEM_TYPE_PAGE_POOL, but shield linker.
*/
#ifdef CONFIG_PAGE_POOL
if (!page_pool_is_last_frag(pool, page))
return;
page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct);
#endif
}
/* Same as above but will try to sync the entire area pool->max_len */
static inline void page_pool_put_full_page(struct page_pool *pool,
struct page *page, bool allow_direct)
{
page_pool_put_page(pool, page, -1, allow_direct);
}
/* Same as above but the caller must guarantee safe context. e.g NAPI */
static inline void page_pool_recycle_direct(struct page_pool *pool,
struct page *page)
{
page_pool_put_full_page(pool, page, true);
}
#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \
(sizeof(dma_addr_t) > sizeof(unsigned long))
static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
{
dma_addr_t ret = page->dma_addr;
if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
return ret;
}
static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
{
page->dma_addr = addr;
if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
page->dma_addr_upper = upper_32_bits(addr);
}
static inline bool is_page_pool_compiled_in(void)
{
#ifdef CONFIG_PAGE_POOL
return true;
#else
return false;
#endif
}
static inline bool page_pool_put(struct page_pool *pool)
{
return refcount_dec_and_test(&pool->user_cnt);
}
/* Caller must provide appropriate safe context, e.g. NAPI. */
void page_pool_update_nid(struct page_pool *pool, int new_nid);
static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
{
if (unlikely(pool->p.nid != new_nid))
page_pool_update_nid(pool, new_nid);
}
static inline void page_pool_ring_lock(struct page_pool *pool)
__acquires(&pool->ring.producer_lock)
{
if (in_softirq())
spin_lock(&pool->ring.producer_lock);
else
spin_lock_bh(&pool->ring.producer_lock);
}
static inline void page_pool_ring_unlock(struct page_pool *pool)
__releases(&pool->ring.producer_lock)
{
if (in_softirq())
spin_unlock(&pool->ring.producer_lock);
else
spin_unlock_bh(&pool->ring.producer_lock);
}
#endif /* _NET_PAGE_POOL_H */