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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 | * If page_pool handles DMA mapping (use page->private), then API user | |
20 | * is responsible for invoking page_pool_put_page() once. In-case of | |
21 | * elevated refcnt, the DMA state is released, assuming other users of | |
22 | * the page will eventually call put_page(). | |
23 | * | |
24 | * If no DMA mapping is done, then it can act as shim-layer that | |
25 | * fall-through to alloc_page. As no state is kept on the page, the | |
26 | * regular put_page() call is sufficient. | |
27 | */ | |
28 | #ifndef _NET_PAGE_POOL_H | |
29 | #define _NET_PAGE_POOL_H | |
30 | ||
31 | #include <linux/mm.h> /* Needed by ptr_ring */ | |
32 | #include <linux/ptr_ring.h> | |
33 | #include <linux/dma-direction.h> | |
34 | ||
35 | #define PP_FLAG_DMA_MAP 1 /* Should page_pool do the DMA map/unmap */ | |
36 | #define PP_FLAG_ALL PP_FLAG_DMA_MAP | |
37 | ||
38 | /* | |
39 | * Fast allocation side cache array/stack | |
40 | * | |
41 | * The cache size and refill watermark is related to the network | |
42 | * use-case. The NAPI budget is 64 packets. After a NAPI poll the RX | |
43 | * ring is usually refilled and the max consumed elements will be 64, | |
44 | * thus a natural max size of objects needed in the cache. | |
45 | * | |
46 | * Keeping room for more objects, is due to XDP_DROP use-case. As | |
47 | * XDP_DROP allows the opportunity to recycle objects directly into | |
48 | * this array, as it shares the same softirq/NAPI protection. If | |
49 | * cache is already full (or partly full) then the XDP_DROP recycles | |
50 | * would have to take a slower code path. | |
51 | */ | |
52 | #define PP_ALLOC_CACHE_SIZE 128 | |
53 | #define PP_ALLOC_CACHE_REFILL 64 | |
54 | struct pp_alloc_cache { | |
55 | u32 count; | |
56 | void *cache[PP_ALLOC_CACHE_SIZE]; | |
57 | }; | |
58 | ||
59 | struct page_pool_params { | |
60 | unsigned int flags; | |
61 | unsigned int order; | |
62 | unsigned int pool_size; | |
63 | int nid; /* Numa node id to allocate from pages from */ | |
64 | struct device *dev; /* device, for DMA pre-mapping purposes */ | |
65 | enum dma_data_direction dma_dir; /* DMA mapping direction */ | |
66 | }; | |
67 | ||
68 | struct page_pool { | |
69 | struct rcu_head rcu; | |
70 | struct page_pool_params p; | |
71 | ||
72 | /* | |
73 | * Data structure for allocation side | |
74 | * | |
75 | * Drivers allocation side usually already perform some kind | |
76 | * of resource protection. Piggyback on this protection, and | |
77 | * require driver to protect allocation side. | |
78 | * | |
79 | * For NIC drivers this means, allocate a page_pool per | |
80 | * RX-queue. As the RX-queue is already protected by | |
81 | * Softirq/BH scheduling and napi_schedule. NAPI schedule | |
82 | * guarantee that a single napi_struct will only be scheduled | |
83 | * on a single CPU (see napi_schedule). | |
84 | */ | |
85 | struct pp_alloc_cache alloc ____cacheline_aligned_in_smp; | |
86 | ||
87 | /* Data structure for storing recycled pages. | |
88 | * | |
89 | * Returning/freeing pages is more complicated synchronization | |
90 | * wise, because free's can happen on remote CPUs, with no | |
91 | * association with allocation resource. | |
92 | * | |
93 | * Use ptr_ring, as it separates consumer and producer | |
94 | * effeciently, it a way that doesn't bounce cache-lines. | |
95 | * | |
96 | * TODO: Implement bulk return pages into this structure. | |
97 | */ | |
98 | struct ptr_ring ring; | |
99 | }; | |
100 | ||
101 | struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); | |
102 | ||
103 | static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool) | |
104 | { | |
105 | gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN); | |
106 | ||
107 | return page_pool_alloc_pages(pool, gfp); | |
108 | } | |
109 | ||
110 | struct page_pool *page_pool_create(const struct page_pool_params *params); | |
111 | ||
112 | void page_pool_destroy(struct page_pool *pool); | |
113 | ||
114 | /* Never call this directly, use helpers below */ | |
115 | void __page_pool_put_page(struct page_pool *pool, | |
116 | struct page *page, bool allow_direct); | |
117 | ||
389ab7f0 JDB |
118 | static inline void page_pool_put_page(struct page_pool *pool, |
119 | struct page *page, bool allow_direct) | |
ff7d6b27 | 120 | { |
57d0a1c1 JDB |
121 | /* When page_pool isn't compiled-in, net/core/xdp.c doesn't |
122 | * allow registering MEM_TYPE_PAGE_POOL, but shield linker. | |
123 | */ | |
124 | #ifdef CONFIG_PAGE_POOL | |
389ab7f0 | 125 | __page_pool_put_page(pool, page, allow_direct); |
57d0a1c1 | 126 | #endif |
ff7d6b27 JDB |
127 | } |
128 | /* Very limited use-cases allow recycle direct */ | |
129 | static inline void page_pool_recycle_direct(struct page_pool *pool, | |
130 | struct page *page) | |
131 | { | |
132 | __page_pool_put_page(pool, page, true); | |
133 | } | |
134 | ||
57d0a1c1 JDB |
135 | static inline bool is_page_pool_compiled_in(void) |
136 | { | |
137 | #ifdef CONFIG_PAGE_POOL | |
138 | return true; | |
139 | #else | |
140 | return false; | |
141 | #endif | |
142 | } | |
143 | ||
ff7d6b27 | 144 | #endif /* _NET_PAGE_POOL_H */ |