[PATCH net-next v2 12/12] page_pool: make sure struct device is stable

From: Jesper Dangaard Brouer <brouer@redhat.com>
To: netdev@vger.kernel.org,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Toke Høiland-Jørgensen" <toke@toke.dk>,
	"Tariq Toukan" <tariqt@mellanox.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>
Cc: toshiaki.makita1@gmail.com, grygorii.strashko@ti.com,
	ivan.khoronzhuk@linaro.org, mcroce@redhat.com
Subject: [PATCH net-next v2 12/12] page_pool: make sure struct device is stable
Date: Tue, 18 Jun 2019 15:06:08 +0200	[thread overview]
Message-ID: <156086316820.27760.15150124176600072481.stgit@firesoul> (raw)
In-Reply-To: <156086304827.27760.11339786046465638081.stgit@firesoul>

For DMA mapping use-case the page_pool keeps a pointer
to the struct device, which is used in DMA map/unmap calls.

For our in-flight handling, we also need to make sure that
the struct device have not disappeared.  This is assured
via using get_device/put_device API.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reported-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
---
 net/core/page_pool.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index f55ab055d543..b366f59885c1 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -8,6 +8,7 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/device.h>
 
 #include <net/page_pool.h>
 #include <linux/dma-direction.h>
@@ -48,6 +49,9 @@ static int page_pool_init(struct page_pool *pool,
 
 	atomic_set(&pool->pages_state_release_cnt, 0);
 
+	if (pool->p.flags & PP_FLAG_DMA_MAP)
+		get_device(pool->p.dev);
+
 	return 0;
 }
 
@@ -360,6 +364,10 @@ void __page_pool_free(struct page_pool *pool)
 		__warn_in_flight(pool);
 
 	ptr_ring_cleanup(&pool->ring, NULL);
+
+	if (pool->p.flags & PP_FLAG_DMA_MAP)
+		put_device(pool->p.dev);
+
 	kfree(pool);
 }
 EXPORT_SYMBOL(__page_pool_free);

