[net-next v1 01/16] net: page_pool: factor out releasing DMA from releasing the page

From: Mina Almasry <almasrymina@google.com>
To: Shailend Chand <shailend@google.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-kselftest@vger.kernel.org, bpf@vger.kernel.org,
	linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org
Cc: "Mina Almasry" <almasrymina@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jeroen de Borst" <jeroendb@google.com>,
	"Praveen Kaligineedi" <pkaligineedi@google.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"David Ahern" <dsahern@kernel.org>,
	"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Yunsheng Lin" <linyunsheng@huawei.com>,
	"Harshitha Ramamurthy" <hramamurthy@google.com>,
	"Shakeel Butt" <shakeelb@google.com>
Subject: [net-next v1 01/16] net: page_pool: factor out releasing DMA from releasing the page
Date: Thu,  7 Dec 2023 16:52:32 -0800	[thread overview]
Message-ID: <20231208005250.2910004-2-almasrymina@google.com> (raw)
In-Reply-To: <20231208005250.2910004-1-almasrymina@google.com>

From: Jakub Kicinski <kuba@kernel.org>

Releasing the DMA mapping will be useful for other types
of pages, so factor it out. Make sure compiler inlines it,
to avoid any regressions.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mina Almasry <almasrymina@google.com>

---

This is implemented by Jakub in his RFC:

https://lore.kernel.org/netdev/f8270765-a27b-6ccf-33ea-cda097168d79@redhat.com/T/

I take no credit for the idea or implementation. This is a critical
dependency of device memory TCP and thus I'm pulling it into this series
to make it revewable and mergable.

---
 net/core/page_pool.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index c2e7c9a6efbe..ca1b3b65c9b5 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -548,21 +548,16 @@ s32 page_pool_inflight(const struct page_pool *pool, bool strict)
 	return inflight;
 }
 
-/* Disconnects a page (from a page_pool).  API users can have a need
- * to disconnect a page (from a page_pool), to allow it to be used as
- * a regular page (that will eventually be returned to the normal
- * page-allocator via put_page).
- */
-static void page_pool_return_page(struct page_pool *pool, struct page *page)
+static __always_inline
+void __page_pool_release_page_dma(struct page_pool *pool, struct page *page)
 {
 	dma_addr_t dma;
-	int count;
 
 	if (!(pool->p.flags & PP_FLAG_DMA_MAP))
 		/* Always account for inflight pages, even if we didn't
 		 * map them
 		 */
-		goto skip_dma_unmap;
+		return;
 
 	dma = page_pool_get_dma_addr(page);
 
@@ -571,7 +566,19 @@ static void page_pool_return_page(struct page_pool *pool, struct page *page)
 			     PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 			     DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
 	page_pool_set_dma_addr(page, 0);
-skip_dma_unmap:
+}
+
+/* Disconnects a page (from a page_pool).  API users can have a need
+ * to disconnect a page (from a page_pool), to allow it to be used as
+ * a regular page (that will eventually be returned to the normal
+ * page-allocator via put_page).
+ */
+void page_pool_return_page(struct page_pool *pool, struct page *page)
+{
+	int count;
+
+	__page_pool_release_page_dma(pool, page);
+
 	page_pool_clear_pp_info(page);
 
 	/* This may be the last page returned, releasing the pool, so
-- 
2.43.0.472.g3155946c3a-goog

