[PATCH] net: Add a WARN_ON_ONCE() to the transmit timeout function

[PATCH] net: Add a WARN_ON_ONCE() to the transmit timeout function

[Arjan van de Ven]

From: Arjan van de Ven <arjan@linux.intel.com>
Subject: [PATCH] net: Add a WARN_ON_ONCE() to the transmit timeout function

WARN_ON_ONCE() gives a stack trace including the full module list.
Having this in the kernel dump for the timeout case in the
generic netdev watchdog will help us see quicker which driver
is involved. It also allows us to collect statistics 
and patterns in terms of which drivers have this event occuring.

Suggested by Andrew Morton

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
 net/sched/sch_generic.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index b741618..d355e5e 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -219,6 +219,7 @@ static void dev_watchdog(unsigned long arg)
 				printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
 				       dev->name);
 				dev->tx_timeout(dev);
+				WARN_ON_ONCE(1);
 			}
 			if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo)))
 				dev_hold(dev);
-- 
1.5.4.5

Re: [PATCH] net: Add a WARN_ON_ONCE() to the transmit timeout function

[David Miller]

From: Arjan van de Ven <arjan@infradead.org>
Date: Thu, 1 May 2008 13:34:24 -0700

> WARN_ON_ONCE() gives a stack trace including the full module list.
> Having this in the kernel dump for the timeout case in the
> generic netdev watchdog will help us see quicker which driver
> is involved. It also allows us to collect statistics 
> and patterns in terms of which drivers have this event occuring.
> 
> Suggested by Andrew Morton
> 
> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

Looks good, applied.