Patchwork 6lowpan: fix lockdep splats

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Submitter Eric Dumazet
Date Feb. 10, 2014, 7:42 p.m.
Message ID <1392061355.6615.52.camel@edumazet-glaptop2.roam.corp.google.com>
Download mbox | patch
Permalink /patch/319041/
State Accepted
Delegated to: David Miller
Headers show

Comments

Eric Dumazet - Feb. 10, 2014, 7:42 p.m.
From: Eric Dumazet <edumazet@google.com>

When a device ndo_start_xmit() calls again dev_queue_xmit(),
lockdep can complain because dev_queue_xmit() is re-entered and the
spinlocks protecting tx queues share a common lockdep class.

Same issue was fixed for bonding/l2tp/ppp in commits 

0daa2303028a6 ("[PATCH] bonding: lockdep annotation")
49ee49202b4ac ("bonding: set qdisc_tx_busylock to avoid LOCKDEP splat")
23d3b8bfb8eb2 ("net: qdisc busylock needs lockdep annotations ")
303c07db487be ("ppp: set qdisc_tx_busylock to avoid LOCKDEP splat ")

Reported-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)



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David Miller - Feb. 11, 2014, 1:51 a.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 10 Feb 2014 11:42:35 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> When a device ndo_start_xmit() calls again dev_queue_xmit(),
> lockdep can complain because dev_queue_xmit() is re-entered and the
> spinlocks protecting tx queues share a common lockdep class.
> 
> Same issue was fixed for bonding/l2tp/ppp in commits 
> 
> 0daa2303028a6 ("[PATCH] bonding: lockdep annotation")
> 49ee49202b4ac ("bonding: set qdisc_tx_busylock to avoid LOCKDEP splat")
> 23d3b8bfb8eb2 ("net: qdisc busylock needs lockdep annotations ")
> 303c07db487be ("ppp: set qdisc_tx_busylock to avoid LOCKDEP splat ")
> 
> Reported-by: Alexander Aring <alex.aring@gmail.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Tested-by: Alexander Aring <alex.aring@gmail.com>

Applied, thanks Eric.
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Patch

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 8bfb40153fe7..8edfea5da572 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -530,7 +530,27 @@  static struct header_ops lowpan_header_ops = {
 	.create	= lowpan_header_create,
 };
 
+static struct lock_class_key lowpan_tx_busylock;
+static struct lock_class_key lowpan_netdev_xmit_lock_key;
+
+static void lowpan_set_lockdep_class_one(struct net_device *dev,
+					 struct netdev_queue *txq,
+					 void *_unused)
+{
+	lockdep_set_class(&txq->_xmit_lock,
+			  &lowpan_netdev_xmit_lock_key);
+}
+
+
+static int lowpan_dev_init(struct net_device *dev)
+{
+	netdev_for_each_tx_queue(dev, lowpan_set_lockdep_class_one, NULL);
+	dev->qdisc_tx_busylock = &lowpan_tx_busylock;
+	return 0;
+}
+
 static const struct net_device_ops lowpan_netdev_ops = {
+	.ndo_init		= lowpan_dev_init,
 	.ndo_start_xmit		= lowpan_xmit,
 	.ndo_set_mac_address	= lowpan_set_address,
 };