page_pool: split types and declarations from page_pool.h

Split types and pure function declarations from page_pool.h
and add them in page_page/types.h, so that C sources can
include page_pool.h and headers should generally only include
page_pool/types.h as suggested by jakub.
Rename page_pool.h to page_pool/helpers.h to have both in
one place.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://lore.kernel.org/r/20230804180529.2483231-2-aleksander.lobakin@intel.com
[Jakub: change microsoft/mana, fix kdoc paths in Documentation]
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 476 insertions, 0 deletions

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
new file mode 100644
index 000000000000..78df91804c87
--- /dev/null
+++ b/include/net/page_pool/helpers.h
@@ -0,0 +1,238 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * page_pool/helpers.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 call page_pool_put_page() where appropriate and only attach
+ * the page to a page_pool-aware objects, like skbs marked for recycling.
+ *
+ * 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_HELPERS_H
+#define _NET_PAGE_POOL_HELPERS_H
+
+#include <net/page_pool/types.h>
+
+#ifdef CONFIG_PAGE_POOL_STATS
+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, void *stats);
+
+/*
+ * Drivers that wish to harvest page pool stats and report them to users
+ * (perhaps via ethtool, debugfs, or another mechanism) can allocate a
+ * struct page_pool_stats call page_pool_get_stats to get stats for the specified pool.
+ */
+bool page_pool_get_stats(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, 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)
+{
+	gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
+
+	return page_pool_alloc_pages(pool, gfp);
+}
+
+static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
+						    unsigned int *offset,
+						    unsigned int size)
+{
+	gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
+
+	return page_pool_alloc_frag(pool, offset, size, gfp);
+}
+
+/**
+ * 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(struct page_pool *pool)
+{
+	return pool->p.dma_dir;
+}
+
+/* pp_frag_count represents the number of writers who can update the page
+ * either by updating skb->data or via DMA mappings for the device.
+ * We can't rely on the page refcnt for that as we don't know who might be
+ * holding page references and we can't reliably destroy or sync DMA mappings
+ * of the fragments.
+ *
+ * When pp_frag_count reaches 0 we can either recycle the page if the page
+ * refcnt is 1 or return it back to the memory allocator and destroy any
+ * mappings we have.
+ */
+static inline void page_pool_fragment_page(struct page *page, long nr)
+{
+	atomic_long_set(&page->pp_frag_count, nr);
+}
+
+static inline long page_pool_defrag_page(struct page *page, long nr)
+{
+	long ret;
+
+	/* If nr == pp_frag_count then we have cleared all remaining
+	 * references to the page. No need to actually overwrite it, instead
+	 * we can leave this to be overwritten by the calling function.
+	 *
+	 * The main advantage to doing this is that an atomic_read is
+	 * generally a much cheaper operation than an atomic update,
+	 * especially when dealing with a page that may be partitioned
+	 * into only 2 or 3 pieces.
+	 */
+	if (atomic_long_read(&page->pp_frag_count) == nr)
+		return 0;
+
+	ret = atomic_long_sub_return(nr, &page->pp_frag_count);
+	WARN_ON(ret < 0);
+	return ret;
+}
+
+static inline bool page_pool_is_last_frag(struct page_pool *pool,
+					  struct page *page)
+{
+	/* If fragments aren't enabled or count is 0 we were the last user */
+	return !(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
+	       (page_pool_defrag_page(page, 1) == 0);
+}
+
+/**
+ * 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)
+{
+	/* 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
+	if (!page_pool_is_last_frag(pool, page))
+		return;
+
+	page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct);
+#endif
+}
+
+/**
+ * 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_put_page(pool, page, -1, 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)
+{
+	page_pool_put_full_page(pool, page, true);
+}
+
+#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT	\
+		(sizeof(dma_addr_t) > sizeof(unsigned long))
+
+/**
+ * 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(struct page *page)
+{
+	dma_addr_t ret = page->dma_addr;
+
+	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+		ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
+
+	return ret;
+}
+
+static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
+{
+	page->dma_addr = addr;
+	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+		page->dma_addr_upper = upper_32_bits(addr);
+}
+
+static inline bool page_pool_put(struct page_pool *pool)
+{
+	return refcount_dec_and_test(&pool->user_cnt);
+}
+
+static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
+{
+	if (unlikely(pool->p.nid != new_nid))
+		page_pool_update_nid(pool, new_nid);
+}
+
+#endif /* _NET_PAGE_POOL_HELPERS_H */
diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
new file mode 100644
index 000000000000..9ac39191bed7
--- /dev/null
+++ b/include/net/page_pool/types.h
@@ -0,0 +1,238 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _NET_PAGE_POOL_TYPES_H
+#define _NET_PAGE_POOL_TYPES_H
+
+#include <linux/dma-direction.h>
+#include <linux/ptr_ring.h>
+
+#define PP_FLAG_DMA_MAP		BIT(0) /* Should page_pool do the DMA
+					* map/unmap
+					*/
+#define PP_FLAG_DMA_SYNC_DEV	BIT(1) /* If set all pages that the driver gets
+					* from page_pool will be
+					* DMA-synced-for-device according to
+					* the length provided by the device
+					* driver.
+					* Please note DMA-sync-for-CPU is still
+					* device driver responsibility
+					*/
+#define PP_FLAG_PAGE_FRAG	BIT(2) /* for page frag feature */
+#define PP_FLAG_ALL		(PP_FLAG_DMA_MAP |\
+				 PP_FLAG_DMA_SYNC_DEV |\
+				 PP_FLAG_PAGE_FRAG)
+
+/*
+ * 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;
+	struct page *cache[PP_ALLOC_CACHE_SIZE];
+};
+
+/**
+ * struct page_pool_params - page pool parameters
+ * @flags:	PP_FLAG_DMA_MAP, PP_FLAG_DMA_SYNC_DEV, PP_FLAG_PAGE_FRAG
+ * @order:	2^order pages on allocation
+ * @pool_size:	size of the ptr_ring
+ * @nid:	NUMA node id to allocate from pages from
+ * @dev:	device, for DMA pre-mapping purposes
+ * @napi:	NAPI which is the sole consumer of pages, otherwise NULL
+ * @dma_dir:	DMA mapping direction
+ * @max_len:	max DMA sync memory size for PP_FLAG_DMA_SYNC_DEV
+ * @offset:	DMA sync address offset for PP_FLAG_DMA_SYNC_DEV
+ */
+struct page_pool_params {
+	unsigned int	flags;
+	unsigned int	order;
+	unsigned int	pool_size;
+	int		nid;
+	struct device	*dev;
+	struct napi_struct *napi;
+	enum dma_data_direction dma_dir;
+	unsigned int	max_len;
+	unsigned int	offset;
+/* private: used by test code only */
+	void (*init_callback)(struct page *page, void *arg);
+	void *init_arg;
+};
+
+#ifdef CONFIG_PAGE_POOL_STATS
+/**
+ * struct page_pool_alloc_stats - allocation statistics
+ * @fast:	successful fast path allocations
+ * @slow:	slow path order-0 allocations
+ * @slow_high_order: slow path high order allocations
+ * @empty:	ptr ring is empty, so a slow path allocation was forced
+ * @refill:	an allocation which triggered a refill of the cache
+ * @waive:	pages obtained from the ptr ring that cannot be added to
+ *		the cache due to a NUMA mismatch
+ */
+struct page_pool_alloc_stats {
+	u64 fast;
+	u64 slow;
+	u64 slow_high_order;
+	u64 empty;
+	u64 refill;
+	u64 waive;
+};
+
+/**
+ * struct page_pool_recycle_stats - recycling (freeing) statistics
+ * @cached:	recycling placed page in the page pool cache
+ * @cache_full:	page pool cache was full
+ * @ring:	page placed into the ptr ring
+ * @ring_full:	page released from page pool because the ptr ring was full
+ * @released_refcnt:	page released (and not recycled) because refcnt > 1
+ */
+struct page_pool_recycle_stats {
+	u64 cached;
+	u64 cache_full;
+	u64 ring;
+	u64 ring_full;
+	u64 released_refcnt;
+};
+
+/**
+ * struct page_pool_stats - combined page pool use statistics
+ * @alloc_stats:	see struct page_pool_alloc_stats
+ * @recycle_stats:	see struct page_pool_recycle_stats
+ *
+ * Wrapper struct for combining page pool stats with different storage
+ * requirements.
+ */
+struct page_pool_stats {
+	struct page_pool_alloc_stats alloc_stats;
+	struct page_pool_recycle_stats recycle_stats;
+};
+#endif
+
+struct page_pool {
+	struct page_pool_params p;
+
+	struct delayed_work release_dw;
+	void (*disconnect)(void *pool);
+	unsigned long defer_start;
+	unsigned long defer_warn;
+
+	u32 pages_state_hold_cnt;
+	unsigned int frag_offset;
+	struct page *frag_page;
+	long frag_users;
+
+#ifdef CONFIG_PAGE_POOL_STATS
+	/* these stats are incremented while in softirq context */
+	struct page_pool_alloc_stats alloc_stats;
+#endif
+	u32 xdp_mem_id;
+
+	/*
+	 * 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
+	 * efficiently, it a way that doesn't bounce cache-lines.
+	 *
+	 * TODO: Implement bulk return pages into this structure.
+	 */
+	struct ptr_ring ring;
+
+#ifdef CONFIG_PAGE_POOL_STATS
+	/* recycle stats are per-cpu to avoid locking */
+	struct page_pool_recycle_stats __percpu *recycle_stats;
+#endif
+	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;
+
+	u64 destroy_cnt;
+};
+
+struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
+struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
+				  unsigned int size, gfp_t gfp);
+bool page_pool_return_skb_page(struct page *page, bool napi_safe);
+
+struct page_pool *page_pool_create(const struct page_pool_params *params);
+
+struct xdp_mem_info;
+
+#ifdef CONFIG_PAGE_POOL
+void page_pool_unlink_napi(struct page_pool *pool);
+void page_pool_destroy(struct page_pool *pool);
+void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
+			   struct xdp_mem_info *mem);
+void page_pool_put_page_bulk(struct page_pool *pool, void **data,
+			     int count);
+#else
+static inline void page_pool_unlink_napi(struct page_pool *pool)
+{
+}
+
+static inline void page_pool_destroy(struct page_pool *pool)
+{
+}
+
+static inline void page_pool_use_xdp_mem(struct page_pool *pool,
+					 void (*disconnect)(void *),
+					 struct xdp_mem_info *mem)
+{
+}
+
+static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
+					   int count)
+{
+}
+#endif
+
+void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
+				  unsigned int dma_sync_size,
+				  bool allow_direct);
+
+static inline bool is_page_pool_compiled_in(void)
+{
+#ifdef CONFIG_PAGE_POOL
+	return true;
+#else
+	return false;
+#endif
+}
+
+/* Caller must provide appropriate safe context, e.g. NAPI. */
+void page_pool_update_nid(struct page_pool *pool, int new_nid);
+
+#endif /* _NET_PAGE_POOL_H */