Patchwork team: set qdisc_tx_busylock to avoid LOCKDEP splat

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Submitter Eric Dumazet
Date Oct. 4, 2012, 9:18 a.m.
Message ID <1349342319.16011.30.camel@edumazet-glaptop>
Download mbox | patch
Permalink /patch/189072/
State Accepted
Delegated to: David Miller
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Comments

Eric Dumazet - Oct. 4, 2012, 9:18 a.m.
From: Eric Dumazet <edumazet@google.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@google.com>
Cc: Jiri Pirko <jpirko@redhat.com>
---
 drivers/net/team/team.c |    2 ++
 1 file changed, 2 insertions(+)



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Jiri Pirko - Oct. 4, 2012, 9:22 a.m.
Thu, Oct 04, 2012 at 11:18:39AM CEST, eric.dumazet@gmail.com wrote:
>From: Eric Dumazet <edumazet@google.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@google.com>
>Cc: Jiri Pirko <jpirko@redhat.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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Thanks Eric.

Acked-by: Jiri Pirko <jiri@resnulli.us>

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David Miller - Oct. 4, 2012, 7:54 p.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 04 Oct 2012 11:18:39 +0200

> From: Eric Dumazet <edumazet@google.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@google.com>
> Cc: Jiri Pirko <jpirko@redhat.com>

Applied.
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Patch

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)