netdev - [PATCH] team: set qdisc_tx_busylock to avoid LOCKDEP splat

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Date:	Thu, 04 Oct 2012 11:18:39 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>, Jiri Pirko <jpirko@...hat.com>
Subject: [PATCH] team: set qdisc_tx_busylock to avoid LOCKDEP splat

From: Eric Dumazet <edumazet@...gle.com>

If a qdisc is installed on a team device, its possible to get
a lockdep splat under stress, because nested dev_queue_xmit() can
lock busylock a second time (on a different device, so its a false
positive)

Avoid this problem using a distinct lock_class_key for team
devices.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jiri Pirko <jpirko@...hat.com>
---
 drivers/net/team/team.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 5c7547c..d44cca3 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -1315,6 +1315,7 @@ static const struct team_option team_options[] = {
 
 static struct lock_class_key team_netdev_xmit_lock_key;
 static struct lock_class_key team_netdev_addr_lock_key;
+static struct lock_class_key team_tx_busylock_key;
 
 static void team_set_lockdep_class_one(struct net_device *dev,
 				       struct netdev_queue *txq,
@@ -1327,6 +1328,7 @@ static void team_set_lockdep_class(struct net_device *dev)
 {
 	lockdep_set_class(&dev->addr_list_lock, &team_netdev_addr_lock_key);
 	netdev_for_each_tx_queue(dev, team_set_lockdep_class_one, NULL);
+	dev->qdisc_tx_busylock = &team_tx_busylock_key;
 }
 
 static int team_init(struct net_device *dev)


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