linux-kernel - Re: [PATCH 01/20 -v5] printk - dont wakeup klogd with interrupts disabled

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Message-ID: <20080123172509.GC22229@Krystal>
Date:	Wed, 23 Jan 2008 12:25:09 -0500
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Daniel Walker <dwalker@...sta.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Christoph Hellwig <hch@...radead.org>,
	Gregory Haskins <ghaskins@...ell.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tim Bird <tim.bird@...sony.com>,
	Sam Ravnborg <sam@...nborg.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	John Stultz <johnstul@...ibm.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 01/20 -v5] printk - dont wakeup klogd with interrupts
	disabled

* Daniel Walker (dwalker@...sta.com) wrote:
> 
> On Wed, 2008-01-23 at 11:02 -0500, Steven Rostedt wrote:
> 
> > +	if (!irqs_disabled() && wake_klogd)
> >  		wake_up_klogd();
> 
> This causes a regression .. When printk is called during an OOPS in
> kernels without this change then the OOPS will get logged, since the
> logging process (klogd) is woken to handle the messages.. If you apply
> this change klogd doesn't wakeup, and hence doesn't log the oops.. So if
> you remove the wakeup here you have to add it someplace else to maintain
> the logging ..
> 
> (I'm not theorizing here, I have defects logged against this specific
> piece of code..)
> 

Can we change this for :
if (!(irqs_disabled() && !oops_in_progress) && wake_klogd)
  wake_up_klogd();

?

(totally untested)

> Daniel
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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