include/net/page_pool.h

   1 /* SPDX-License-Identifier: GPL-2.0
   2  *
   3  * page_pool.h
   4  *      Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
   5  *      Copyright (C) 2016 Red Hat, Inc.
   6  */
   7
   8 /**
   9  * DOC: page_pool allocator
  10  *
  11  * This page_pool allocator is optimized for the XDP mode that
  12  * uses one-frame-per-page, but have fallbacks that act like the
  13  * regular page allocator APIs.
  14  *
  15  * Basic use involve replacing alloc_pages() calls with the
  16  * page_pool_alloc_pages() call.  Drivers should likely use
  17  * page_pool_dev_alloc_pages() replacing dev_alloc_pages().
  18  *
  19  * API keeps track of in-flight pages, in-order to let API user know
  20  * when it is safe to dealloactor page_pool object.  Thus, API users
  21  * must make sure to call page_pool_release_page() when a page is
  22  * "leaving" the page_pool.  Or call page_pool_put_page() where
  23  * appropiate.  For maintaining correct accounting.
  24  *
  25  * API user must only call page_pool_put_page() once on a page, as it
  26  * will either recycle the page, or in case of elevated refcnt, it
  27  * will release the DMA mapping and in-flight state accounting.  We
  28  * hope to lift this requirement in the future.
  29  */
  30 #ifndef _NET_PAGE_POOL_H
  31 #define _NET_PAGE_POOL_H
  32
  33 #include <linux/mm.h> /* Needed by ptr_ring */
  34 #include <linux/ptr_ring.h>
  35 #include <linux/dma-direction.h>
  36
  37 #define PP_FLAG_DMA_MAP         BIT(0) /* Should page_pool do the DMA
  38                                         * map/unmap
  39                                         */
  40 #define PP_FLAG_DMA_SYNC_DEV    BIT(1) /* If set all pages that the driver gets
  41                                         * from page_pool will be
  42                                         * DMA-synced-for-device according to
  43                                         * the length provided by the device
  44                                         * driver.
  45                                         * Please note DMA-sync-for-CPU is still
  46                                         * device driver responsibility
  47                                         */
  48 #define PP_FLAG_ALL             (PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV)
  49
  50 /*
  51  * Fast allocation side cache array/stack
  52  *
  53  * The cache size and refill watermark is related to the network
  54  * use-case.  The NAPI budget is 64 packets.  After a NAPI poll the RX
  55  * ring is usually refilled and the max consumed elements will be 64,
  56  * thus a natural max size of objects needed in the cache.
  57  *
  58  * Keeping room for more objects, is due to XDP_DROP use-case.  As
  59  * XDP_DROP allows the opportunity to recycle objects directly into
  60  * this array, as it shares the same softirq/NAPI protection.  If
  61  * cache is already full (or partly full) then the XDP_DROP recycles
  62  * would have to take a slower code path.
  63  */
  64 #define PP_ALLOC_CACHE_SIZE     128
  65 #define PP_ALLOC_CACHE_REFILL   64
  66 struct pp_alloc_cache {
  67         u32 count;
  68         void *cache[PP_ALLOC_CACHE_SIZE];
  69 };
  70
  71 struct page_pool_params {
  72         unsigned int    flags;
  73         unsigned int    order;
  74         unsigned int    pool_size;
  75         int             nid;  /* Numa node id to allocate from pages from */
  76         struct device   *dev; /* device, for DMA pre-mapping purposes */
  77         enum dma_data_direction dma_dir; /* DMA mapping direction */
  78         unsigned int    max_len; /* max DMA sync memory size */
  79         unsigned int    offset;  /* DMA addr offset */
  80 };
  81
  82 struct page_pool {
  83         struct page_pool_params p;
  84
  85         struct delayed_work release_dw;
  86         void (*disconnect)(void *);
  87         unsigned long defer_start;
  88         unsigned long defer_warn;
  89
  90         u32 pages_state_hold_cnt;
  91
  92         /*
  93          * Data structure for allocation side
  94          *
  95          * Drivers allocation side usually already perform some kind
  96          * of resource protection.  Piggyback on this protection, and
  97          * require driver to protect allocation side.
  98          *
  99          * For NIC drivers this means, allocate a page_pool per
 100          * RX-queue. As the RX-queue is already protected by
 101          * Softirq/BH scheduling and napi_schedule. NAPI schedule
 102          * guarantee that a single napi_struct will only be scheduled
 103          * on a single CPU (see napi_schedule).
 104          */
 105         struct pp_alloc_cache alloc ____cacheline_aligned_in_smp;
 106
 107         /* Data structure for storing recycled pages.
 108          *
 109          * Returning/freeing pages is more complicated synchronization
 110          * wise, because free's can happen on remote CPUs, with no
 111          * association with allocation resource.
 112          *
 113          * Use ptr_ring, as it separates consumer and producer
 114          * effeciently, it a way that doesn't bounce cache-lines.
 115          *
 116          * TODO: Implement bulk return pages into this structure.
 117          */
 118         struct ptr_ring ring;
 119
 120         atomic_t pages_state_release_cnt;
 121
 122         /* A page_pool is strictly tied to a single RX-queue being
 123          * protected by NAPI, due to above pp_alloc_cache. This
 124          * refcnt serves purpose is to simplify drivers error handling.
 125          */
 126         refcount_t user_cnt;
 127
 128         u64 destroy_cnt;
 129 };
 130
 131 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
 132
 133 static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
 134 {
 135         gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
 136
 137         return page_pool_alloc_pages(pool, gfp);
 138 }
 139
 140 /* get the stored dma direction. A driver might decide to treat this locally and
 141  * avoid the extra cache line from page_pool to determine the direction
 142  */
 143 static
 144 inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
 145 {
 146         return pool->p.dma_dir;
 147 }
 148
 149 struct page_pool *page_pool_create(const struct page_pool_params *params);
 150
 151 #ifdef CONFIG_PAGE_POOL
 152 void page_pool_destroy(struct page_pool *pool);
 153 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *));
 154 void page_pool_release_page(struct page_pool *pool, struct page *page);
 155 #else
 156 static inline void page_pool_destroy(struct page_pool *pool)
 157 {
 158 }
 159
 160 static inline void page_pool_use_xdp_mem(struct page_pool *pool,
 161                                          void (*disconnect)(void *))
 162 {
 163 }
 164 static inline void page_pool_release_page(struct page_pool *pool,
 165                                           struct page *page)
 166 {
 167 }
 168 #endif
 169
 170 void page_pool_put_page(struct page_pool *pool, struct page *page,
 171                         unsigned int dma_sync_size, bool allow_direct);
 172
 173 /* Same as above but will try to sync the entire area pool->max_len */
 174 static inline void page_pool_put_full_page(struct page_pool *pool,
 175                                            struct page *page, bool allow_direct)
 176 {
 177         /* When page_pool isn't compiled-in, net/core/xdp.c doesn't
 178          * allow registering MEM_TYPE_PAGE_POOL, but shield linker.
 179          */
 180 #ifdef CONFIG_PAGE_POOL
 181         page_pool_put_page(pool, page, -1, allow_direct);
 182 #endif
 183 }
 184
 185 /* Same as above but the caller must guarantee safe context. e.g NAPI */
 186 static inline void page_pool_recycle_direct(struct page_pool *pool,
 187                                             struct page *page)
 188 {
 189         page_pool_put_full_page(pool, page, true);
 190 }
 191
 192 static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 193 {
 194         return page->dma_addr;
 195 }
 196
 197 static inline bool is_page_pool_compiled_in(void)
 198 {
 199 #ifdef CONFIG_PAGE_POOL
 200         return true;
 201 #else
 202         return false;
 203 #endif
 204 }
 205
 206 static inline bool page_pool_put(struct page_pool *pool)
 207 {
 208         return refcount_dec_and_test(&pool->user_cnt);
 209 }
 210
 211 /* Caller must provide appropriate safe context, e.g. NAPI. */
 212 void page_pool_update_nid(struct page_pool *pool, int new_nid);
 213 static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
 214 {
 215         if (unlikely(pool->p.nid != new_nid))
 216                 page_pool_update_nid(pool, new_nid);
 217 }
 218 #endif /* _NET_PAGE_POOL_H */