linux-kernel - [PATCH 3.19 08/27] openvswitch: Return vport module ref before destruction

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Date:	Sun, 26 Apr 2015 16:15:39 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Pravin Shelar <pshelar@...ira.com>,
	Thomas Graf <tgraf@...g.ch>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.19 08/27] openvswitch: Return vport module ref before destruction

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Graf <tgraf@...g.ch>

[ Upstream commit fa2d8ff4e3522b4e05f590575d3eb8087f3a8cdc ]

Return module reference before invoking the respective vport
->destroy() function. This is needed as ovs_vport_del() is not
invoked inside an RCU read side critical section so the kfree
can occur immediately before returning to ovs_vport_del().

Returning the module reference before ->destroy() is safe because
the module unregistration is blocked on ovs_lock which we hold
while destroying the datapath.

Fixes: 62b9c8d0372d ("ovs: Turn vports with dependencies into separate modules")
Reported-by: Pravin Shelar <pshelar@...ira.com>
Signed-off-by: Thomas Graf <tgraf@...g.ch>
Acked-by: Pravin B Shelar <pshelar@...ira.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/openvswitch/vport.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -274,10 +274,8 @@ void ovs_vport_del(struct vport *vport)
 	ASSERT_OVSL();
 
 	hlist_del_rcu(&vport->hash_node);
-
-	vport->ops->destroy(vport);
-
 	module_put(vport->ops->owner);
+	vport->ops->destroy(vport);
 }
 
 /**


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