/* SPDX-License-Identifier: GPL-2.0 * * page_pool/helpers.h * Author: Jesper Dangaard Brouer <[email protected]> * Copyright (C) 2016 Red Hat, Inc. */ /** * DOC: page_pool allocator * * The page_pool allocator is optimized for recycling page or page fragment used * by skb packet and xdp frame. * * Basic use involves replacing any alloc_pages() calls with page_pool_alloc(), * which allocate memory with or without page splitting depending on the * requested memory size. * * If the driver knows that it always requires full pages or its allocations are * always smaller than half a page, it can use one of the more specific API * calls: * * 1. page_pool_alloc_pages(): allocate memory without page splitting when * driver knows that the memory it need is always bigger than half of the page * allocated from page pool. There is no cache line dirtying for 'struct page' * when a page is recycled back to the page pool. * * 2. page_pool_alloc_frag(): allocate memory with page splitting when driver * knows that the memory it need is always smaller than or equal to half of the * page allocated from page pool. Page splitting enables memory saving and thus * avoids TLB/cache miss for data access, but there also is some cost to * implement page splitting, mainly some cache line dirtying/bouncing for * 'struct page' and atomic operation for page->pp_ref_count. * * The API keeps track of in-flight pages, in order to let API users know when * it is safe to free a page_pool object, the API users must call * page_pool_put_page() or page_pool_free_va() to free the page_pool object, or * attach the page_pool object to a page_pool-aware object like skbs marked with * skb_mark_for_recycle(). * * page_pool_put_page() may be called multiple times on the same page if a page * is split into multiple fragments. For the last fragment, it will either * recycle the page, or in case of page->_refcount > 1, it will release the DMA * mapping and in-flight state accounting. * * dma_sync_single_range_for_device() is only called for the last fragment when * page_pool is created with PP_FLAG_DMA_SYNC_DEV flag, so it depends on the * last freed fragment to do the sync_for_device operation for all fragments in * the same page when a page is split. The API user must setup pool->p.max_len * and pool->p.offset correctly and ensure that page_pool_put_page() is called * with dma_sync_size being -1 for fragment API. */ #ifndef _NET_PAGE_POOL_HELPERS_H #define _NET_PAGE_POOL_HELPERS_H #include <linux/dma-mapping.h> #include <net/page_pool/types.h> #include <net/net_debug.h> #include <net/netmem.h> #ifdef CONFIG_PAGE_POOL_STATS /* Deprecated driver-facing API, use netlink instead */ 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, const void *stats); bool page_pool_get_stats(const 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, const void *stats) { return data; } #endif /** * page_pool_dev_alloc_pages() - allocate a page. * @pool: pool from which to allocate * * Get a page from the page allocator or page_pool caches. */ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool) { … } /** * page_pool_dev_alloc_frag() - allocate a page fragment. * @pool: pool from which to allocate * @offset: offset to the allocated page * @size: requested size * * Get a page fragment from the page allocator or page_pool caches. * * Return: * Return allocated page fragment, otherwise return NULL. */ static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool, unsigned int *offset, unsigned int size) { … } static inline struct page *page_pool_alloc(struct page_pool *pool, unsigned int *offset, unsigned int *size, gfp_t gfp) { … } /** * page_pool_dev_alloc() - allocate a page or a page fragment. * @pool: pool from which to allocate * @offset: offset to the allocated page * @size: in as the requested size, out as the allocated size * * Get a page or a page fragment from the page allocator or page_pool caches * depending on the requested size in order to allocate memory with least memory * utilization and performance penalty. * * Return: * Return allocated page or page fragment, otherwise return NULL. */ static inline struct page *page_pool_dev_alloc(struct page_pool *pool, unsigned int *offset, unsigned int *size) { … } static inline void *page_pool_alloc_va(struct page_pool *pool, unsigned int *size, gfp_t gfp) { … } /** * page_pool_dev_alloc_va() - allocate a page or a page fragment and return its * va. * @pool: pool from which to allocate * @size: in as the requested size, out as the allocated size * * This is just a thin wrapper around the page_pool_alloc() API, and * it returns va of the allocated page or page fragment. * * Return: * Return the va for the allocated page or page fragment, otherwise return NULL. */ static inline void *page_pool_dev_alloc_va(struct page_pool *pool, unsigned int *size) { … } /** * page_pool_get_dma_dir() - Retrieve the stored DMA direction. * @pool: pool from which page was allocated * * Get the stored dma direction. A driver might decide to store 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(const struct page_pool *pool) { … } static inline void page_pool_fragment_netmem(netmem_ref netmem, long nr) { … } /** * page_pool_fragment_page() - split a fresh page into fragments * @page: page to split * @nr: references to set * * pp_ref_count represents the number of outstanding references to the page, * which will be freed using page_pool APIs (rather than page allocator APIs * like put_page()). Such references are usually held by page_pool-aware * objects like skbs marked for page pool recycling. * * This helper allows the caller to take (set) multiple references to a * freshly allocated page. The page must be freshly allocated (have a * pp_ref_count of 1). This is commonly done by drivers and * "fragment allocators" to save atomic operations - either when they know * upfront how many references they will need; or to take MAX references and * return the unused ones with a single atomic dec(), instead of performing * multiple atomic inc() operations. */ static inline void page_pool_fragment_page(struct page *page, long nr) { … } static inline long page_pool_unref_netmem(netmem_ref netmem, long nr) { … } static inline long page_pool_unref_page(struct page *page, long nr) { … } static inline void page_pool_ref_netmem(netmem_ref netmem) { … } static inline void page_pool_ref_page(struct page *page) { … } static inline bool page_pool_is_last_ref(netmem_ref netmem) { … } static inline void page_pool_put_netmem(struct page_pool *pool, netmem_ref netmem, unsigned int dma_sync_size, bool allow_direct) { … } /** * page_pool_put_page() - release a reference to a page pool page * @pool: pool from which page was allocated * @page: page to release a reference on * @dma_sync_size: how much of the page may have been touched by the device * @allow_direct: released by the consumer, allow lockless caching * * The outcome of this depends on the page refcnt. If the driver bumps * the refcnt > 1 this will unmap the page. If the page refcnt is 1 * the allocator owns the page and will try to recycle it in one of the pool * caches. If PP_FLAG_DMA_SYNC_DEV is set, the page will be synced for_device * using dma_sync_single_range_for_device(). */ static inline void page_pool_put_page(struct page_pool *pool, struct page *page, unsigned int dma_sync_size, bool allow_direct) { … } static inline void page_pool_put_full_netmem(struct page_pool *pool, netmem_ref netmem, bool allow_direct) { … } /** * page_pool_put_full_page() - release a reference on a page pool page * @pool: pool from which page was allocated * @page: page to release a reference on * @allow_direct: released by the consumer, allow lockless caching * * Similar to page_pool_put_page(), but will DMA sync the entire memory area * as configured in &page_pool_params.max_len. */ static inline void page_pool_put_full_page(struct page_pool *pool, struct page *page, bool allow_direct) { … } /** * page_pool_recycle_direct() - release a reference on a page pool page * @pool: pool from which page was allocated * @page: page to release a reference on * * Similar to page_pool_put_full_page() but caller must guarantee safe context * (e.g NAPI), since it will recycle the page directly into the pool fast cache. */ static inline void page_pool_recycle_direct(struct page_pool *pool, struct page *page) { … } #define PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA … /** * page_pool_free_va() - free a va into the page_pool * @pool: pool from which va was allocated * @va: va to be freed * @allow_direct: freed by the consumer, allow lockless caching * * Free a va allocated from page_pool_allo_va(). */ static inline void page_pool_free_va(struct page_pool *pool, void *va, bool allow_direct) { … } static inline dma_addr_t page_pool_get_dma_addr_netmem(netmem_ref netmem) { … } /** * page_pool_get_dma_addr() - Retrieve the stored DMA address. * @page: page allocated from a page pool * * Fetch the DMA address of the page. The page pool to which the page belongs * must had been created with PP_FLAG_DMA_MAP. */ static inline dma_addr_t page_pool_get_dma_addr(const struct page *page) { … } static inline bool page_pool_set_dma_addr_netmem(netmem_ref netmem, dma_addr_t addr) { … } /** * page_pool_dma_sync_for_cpu - sync Rx page for CPU after it's written by HW * @pool: &page_pool the @page belongs to * @page: page to sync * @offset: offset from page start to "hard" start if using PP frags * @dma_sync_size: size of the data written to the page * * Can be used as a shorthand to sync Rx pages before accessing them in the * driver. Caller must ensure the pool was created with ``PP_FLAG_DMA_MAP``. * Note that this version performs DMA sync unconditionally, even if the * associated PP doesn't perform sync-for-device. */ static inline void page_pool_dma_sync_for_cpu(const struct page_pool *pool, const struct page *page, u32 offset, u32 dma_sync_size) { … } static inline bool page_pool_set_dma_addr(struct page *page, dma_addr_t addr) { … } static inline bool page_pool_put(struct page_pool *pool) { … } static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid) { … } #endif /* _NET_PAGE_POOL_HELPERS_H */
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