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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 1 /* Should page_pool do the DMA map/unmap */
#define PP_FLAG_ALL PP_FLAG_DMA_MAP
/*
* 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;
void *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 */
};
struct page_pool {
struct page_pool_params p;
u32 pages_state_hold_cnt;
/*
* 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;
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;
};
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);
}
/* 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;
}
struct page_pool *page_pool_create(const struct page_pool_params *params);
void __page_pool_free(struct page_pool *pool);
static inline void page_pool_free(struct page_pool *pool)
{
/* 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
__page_pool_free(pool);
#endif
}
/* Drivers use this instead of page_pool_free */
static inline void page_pool_destroy(struct page_pool *pool)
{
if (!pool)
return;
page_pool_free(pool);
}
/* Never call this directly, use helpers below */
void __page_pool_put_page(struct page_pool *pool,
struct page *page, bool allow_direct);
static inline void page_pool_put_page(struct page_pool *pool,
struct page *page, 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
__page_pool_put_page(pool, page, allow_direct);
#endif
}
/* Very limited use-cases allow recycle direct */
static inline void page_pool_recycle_direct(struct page_pool *pool,
struct page *page)
{
__page_pool_put_page(pool, page, true);
}
/* API user MUST have disconnected alloc-side (not allowed to call
* page_pool_alloc_pages()) before calling this. The free-side can
* still run concurrently, to handle in-flight packet-pages.
*
* A request to shutdown can fail (with false) if there are still
* in-flight packet-pages.
*/
bool __page_pool_request_shutdown(struct page_pool *pool);
static inline bool page_pool_request_shutdown(struct page_pool *pool)
{
bool safe_to_remove = false;
#ifdef CONFIG_PAGE_POOL
safe_to_remove = __page_pool_request_shutdown(pool);
#endif
return safe_to_remove;
}
/* 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_unmap_page(struct page_pool *pool, struct page *page);
static inline void page_pool_release_page(struct page_pool *pool,
struct page *page)
{
#ifdef CONFIG_PAGE_POOL
page_pool_unmap_page(pool, page);
#endif
}
static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
{
return page->dma_addr;
}
static inline bool is_page_pool_compiled_in(void)
{
#ifdef CONFIG_PAGE_POOL
return true;
#else
return false;
#endif
}
static inline void page_pool_get(struct page_pool *pool)
{
refcount_inc(&pool->user_cnt);
}
static inline bool page_pool_put(struct page_pool *pool)
{
return refcount_dec_and_test(&pool->user_cnt);
}
#endif /* _NET_PAGE_POOL_H */
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