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![Ivan Khoronzhuk](/assets/img/avatar_default.png)
Jesper recently removed page_pool_destroy() (from driver invocation)
and moved shutdown and free of page_pool into xdp_rxq_info_unreg(),
in-order to handle in-flight packets/pages. This created an asymmetry
in drivers create/destroy pairs.
This patch reintroduce page_pool_destroy and add page_pool user
refcnt. This serves the purpose to simplify drivers error handling as
driver now drivers always calls page_pool_destroy() and don't need to
track if xdp_rxq_info_reg_mem_model() was unsuccessful.
This could be used for a special cases where a single RX-queue (with a
single page_pool) provides packets for two net_device'es, and thus
needs to register the same page_pool twice with two xdp_rxq_info
structures.
This patch is primarily to ease API usage for drivers. The recently
merged netsec driver, actually have a bug in this area, which is
solved by this API change.
This patch is a modified version of Ivan Khoronzhuk's original patch.
Link: https://lore.kernel.org/netdev/20190625175948.24771-2-ivan.khoronzhuk@linaro.org/
Fixes: 5c67bf0ec4
("net: netsec: Use page_pool API")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
229 lines
6.8 KiB
C
229 lines
6.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* page_pool.h
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* Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
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* Copyright (C) 2016 Red Hat, Inc.
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*/
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/**
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* DOC: page_pool allocator
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*
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* This page_pool allocator is optimized for the XDP mode that
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* uses one-frame-per-page, but have fallbacks that act like the
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* regular page allocator APIs.
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*
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* Basic use involve replacing alloc_pages() calls with the
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* page_pool_alloc_pages() call. Drivers should likely use
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* page_pool_dev_alloc_pages() replacing dev_alloc_pages().
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*
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* API keeps track of in-flight pages, in-order to let API user know
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* when it is safe to dealloactor page_pool object. Thus, API users
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* must make sure to call page_pool_release_page() when a page is
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* "leaving" the page_pool. Or call page_pool_put_page() where
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* appropiate. For maintaining correct accounting.
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*
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* API user must only call page_pool_put_page() once on a page, as it
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* will either recycle the page, or in case of elevated refcnt, it
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* will release the DMA mapping and in-flight state accounting. We
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* hope to lift this requirement in the future.
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*/
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#ifndef _NET_PAGE_POOL_H
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#define _NET_PAGE_POOL_H
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#include <linux/mm.h> /* Needed by ptr_ring */
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#include <linux/ptr_ring.h>
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#include <linux/dma-direction.h>
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#define PP_FLAG_DMA_MAP 1 /* Should page_pool do the DMA map/unmap */
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#define PP_FLAG_ALL PP_FLAG_DMA_MAP
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/*
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* Fast allocation side cache array/stack
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*
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* The cache size and refill watermark is related to the network
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* use-case. The NAPI budget is 64 packets. After a NAPI poll the RX
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* ring is usually refilled and the max consumed elements will be 64,
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* thus a natural max size of objects needed in the cache.
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*
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* Keeping room for more objects, is due to XDP_DROP use-case. As
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* XDP_DROP allows the opportunity to recycle objects directly into
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* this array, as it shares the same softirq/NAPI protection. If
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* cache is already full (or partly full) then the XDP_DROP recycles
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* would have to take a slower code path.
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*/
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#define PP_ALLOC_CACHE_SIZE 128
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#define PP_ALLOC_CACHE_REFILL 64
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struct pp_alloc_cache {
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u32 count;
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void *cache[PP_ALLOC_CACHE_SIZE];
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};
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struct page_pool_params {
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unsigned int flags;
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unsigned int order;
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unsigned int pool_size;
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int nid; /* Numa node id to allocate from pages from */
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struct device *dev; /* device, for DMA pre-mapping purposes */
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enum dma_data_direction dma_dir; /* DMA mapping direction */
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};
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struct page_pool {
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struct page_pool_params p;
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u32 pages_state_hold_cnt;
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/*
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* Data structure for allocation side
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*
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* Drivers allocation side usually already perform some kind
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* of resource protection. Piggyback on this protection, and
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* require driver to protect allocation side.
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*
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* For NIC drivers this means, allocate a page_pool per
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* RX-queue. As the RX-queue is already protected by
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* Softirq/BH scheduling and napi_schedule. NAPI schedule
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* guarantee that a single napi_struct will only be scheduled
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* on a single CPU (see napi_schedule).
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*/
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struct pp_alloc_cache alloc ____cacheline_aligned_in_smp;
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/* Data structure for storing recycled pages.
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*
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* Returning/freeing pages is more complicated synchronization
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* wise, because free's can happen on remote CPUs, with no
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* association with allocation resource.
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*
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* Use ptr_ring, as it separates consumer and producer
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* effeciently, it a way that doesn't bounce cache-lines.
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*
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* TODO: Implement bulk return pages into this structure.
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*/
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struct ptr_ring ring;
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atomic_t pages_state_release_cnt;
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/* A page_pool is strictly tied to a single RX-queue being
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* protected by NAPI, due to above pp_alloc_cache. This
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* refcnt serves purpose is to simplify drivers error handling.
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*/
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refcount_t user_cnt;
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};
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struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
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static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
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{
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gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
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return page_pool_alloc_pages(pool, gfp);
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}
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/* get the stored dma direction. A driver might decide to treat this locally and
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* avoid the extra cache line from page_pool to determine the direction
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*/
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static
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inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
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{
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return pool->p.dma_dir;
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}
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struct page_pool *page_pool_create(const struct page_pool_params *params);
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void __page_pool_free(struct page_pool *pool);
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static inline void page_pool_free(struct page_pool *pool)
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{
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/* When page_pool isn't compiled-in, net/core/xdp.c doesn't
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* allow registering MEM_TYPE_PAGE_POOL, but shield linker.
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*/
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#ifdef CONFIG_PAGE_POOL
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__page_pool_free(pool);
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#endif
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}
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/* Drivers use this instead of page_pool_free */
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static inline void page_pool_destroy(struct page_pool *pool)
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{
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if (!pool)
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return;
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page_pool_free(pool);
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}
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/* Never call this directly, use helpers below */
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void __page_pool_put_page(struct page_pool *pool,
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struct page *page, bool allow_direct);
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static inline void page_pool_put_page(struct page_pool *pool,
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struct page *page, bool allow_direct)
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{
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/* When page_pool isn't compiled-in, net/core/xdp.c doesn't
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* allow registering MEM_TYPE_PAGE_POOL, but shield linker.
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*/
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#ifdef CONFIG_PAGE_POOL
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__page_pool_put_page(pool, page, allow_direct);
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#endif
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}
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/* Very limited use-cases allow recycle direct */
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static inline void page_pool_recycle_direct(struct page_pool *pool,
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struct page *page)
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{
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__page_pool_put_page(pool, page, true);
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}
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/* API user MUST have disconnected alloc-side (not allowed to call
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* page_pool_alloc_pages()) before calling this. The free-side can
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* still run concurrently, to handle in-flight packet-pages.
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*
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* A request to shutdown can fail (with false) if there are still
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* in-flight packet-pages.
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*/
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bool __page_pool_request_shutdown(struct page_pool *pool);
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static inline bool page_pool_request_shutdown(struct page_pool *pool)
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{
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bool safe_to_remove = false;
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#ifdef CONFIG_PAGE_POOL
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safe_to_remove = __page_pool_request_shutdown(pool);
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#endif
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return safe_to_remove;
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}
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/* Disconnects a page (from a page_pool). API users can have a need
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* to disconnect a page (from a page_pool), to allow it to be used as
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* a regular page (that will eventually be returned to the normal
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* page-allocator via put_page).
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*/
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void page_pool_unmap_page(struct page_pool *pool, struct page *page);
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static inline void page_pool_release_page(struct page_pool *pool,
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struct page *page)
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{
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#ifdef CONFIG_PAGE_POOL
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page_pool_unmap_page(pool, page);
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#endif
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}
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static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
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{
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return page->dma_addr;
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}
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static inline bool is_page_pool_compiled_in(void)
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{
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#ifdef CONFIG_PAGE_POOL
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return true;
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#else
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return false;
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#endif
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}
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static inline void page_pool_get(struct page_pool *pool)
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{
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refcount_inc(&pool->user_cnt);
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}
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static inline bool page_pool_put(struct page_pool *pool)
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{
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return refcount_dec_and_test(&pool->user_cnt);
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}
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#endif /* _NET_PAGE_POOL_H */
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