netdev - [PATCH net-next 1/2] page_pool: support non-split page with PP_FLAG_PAGE

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Date:   Mon, 30 Aug 2021 09:18:09 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...neuler.org>, <hawk@...nel.org>,
        <ilias.apalodimas@...aro.org>, <jonathan.lemon@...il.com>,
        <alobakin@...me>, <willemb@...gle.com>, <cong.wang@...edance.com>,
        <pabeni@...hat.com>, <haokexin@...il.com>, <nogikh@...gle.com>,
        <elver@...gle.com>, <memxor@...il.com>, <edumazet@...gle.com>,
        <alexander.duyck@...il.com>, <dsahern@...il.com>
Subject: [PATCH net-next 1/2] page_pool: support non-split page with PP_FLAG_PAGE_FRAG

Currently when PP_FLAG_PAGE_FRAG is set, the caller is not
expected to call page_pool_alloc_pages() directly because of
the PP_FLAG_PAGE_FRAG checking in __page_pool_put_page().

The patch removes the above checking to enable non-split page
support when PP_FLAG_PAGE_FRAG is set.

Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
---
 include/net/page_pool.h |  6 ++++++
 net/core/page_pool.c    | 12 +++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index a408240..2ad0706 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -238,6 +238,9 @@ static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
 
 static inline void page_pool_set_frag_count(struct page *page, long nr)
 {
+	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+		return;
+
 	atomic_long_set(&page->pp_frag_count, nr);
 }
 
@@ -246,6 +249,9 @@ static inline long page_pool_atomic_sub_frag_count_return(struct page *page,
 {
 	long ret;
 
+	if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+		return 0;
+
 	/* As suggested by Alexander, atomic_long_read() may cover up the
 	 * reference count errors, so avoid calling atomic_long_read() in
 	 * the cases of freeing or draining the page_frags, where we would
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a69784..ba9f14d 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -313,11 +313,14 @@ struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp)
 
 	/* Fast-path: Get a page from cache */
 	page = __page_pool_get_cached(pool);
-	if (page)
-		return page;
 
 	/* Slow-path: cache empty, do real allocation */
-	page = __page_pool_alloc_pages_slow(pool, gfp);
+	if (!page)
+		page = __page_pool_alloc_pages_slow(pool, gfp);
+
+	if (likely(page))
+		page_pool_set_frag_count(page, 1);
+
 	return page;
 }
 EXPORT_SYMBOL(page_pool_alloc_pages);
@@ -426,8 +429,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
 		     unsigned int dma_sync_size, bool allow_direct)
 {
 	/* It is not the last user for the page frag case */
-	if (pool->p.flags & PP_FLAG_PAGE_FRAG &&
-	    page_pool_atomic_sub_frag_count_return(page, 1))
+	if (page_pool_atomic_sub_frag_count_return(page, 1))
 		return NULL;
 
 	/* This allocator is optimized for the XDP mode that uses
-- 
2.7.4