linux-kernel - Re: locking issue (hardirq+softirq+user)

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Date:	Wed, 20 Dec 2006 14:50:18 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: locking issue (hardirq+softirq+user)

On Wed, 2006-12-20 at 14:35 +0100, Jiri Slaby wrote:
> Hi!
> 
> an user still gets NMI watchdog warning, that the machine deadlocked.

have you tried enabling LOCKDEP ?


> isr() /* i.e. hardirq context */
> {
> spin_lock(&lock);
> ...
> spin_unlock(&lock);
> }

this is ok if you are 100% sure that this never gets called in any other
way

> 
> timer() /* i.e. softirq context */
> {
> unsigned int f;
> spin_lock_irqsave(&lock, f) /* stack shows, that it locks here */

this is a bug, the flags are an "unsigned long" not "unsigned int"!
It may do really bad stuff!

Greetings,
   Arjan van de Ven

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

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