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      ˆl–Ým_J*j"Tâ€zã/\m¥1hßÉ0ÄÇ     ˆÃÉ„N²×ÂÄÇ 9Ž    /* 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
 *
 * 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>

#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)
{
	gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);

	return page_pool_alloc_pages(pool, gfp);
}

/**
 * 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)
{
	gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);