linux-kernel - Re: [PATCH 1/2] watchdog: Fix output

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Message-ID: <alpine.LNX.2.00.1603190136470.3656@cbobk.fhfr.pm>
Date:	Sat, 19 Mar 2016 01:39:07 +0100 (CET)
From:	Jiri Kosina <jikos@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Don Zickus <dzickus@...hat.com>, linux-kernel@...r.kernel.org,
	rostedt@...dmis.org, mingo@...nel.org, tglx@...utronix.de
Subject: Re: [PATCH 1/2] watchdog: Fix output

On Sat, 19 Mar 2016, Jiri Kosina wrote:

> > It was Jiri who made this mess by replacing WARN(), which has a very
> > distinct format, with this custom stuff.
> 
> Right, this was in 55537871e ("kernel/watchdog.c: perform all-CPU 
> backtrace in case of hard lockup").
> 
> To be really honest, I don't really have 100% reliable explanation why I 
> did it this way; I *think* it was because otherwise, in case WARN is 
> preserved, we'll either
> 
> - have different output format for current (warning) CPU and all the 
>   others (trigger_allbutself_cpu_backtrace())
> 
> or
> 
> - have duplicated backtrace for current CPU, one coming from WARN and one 
>   coming from the all-cpu backtrace
> 
> > I think we should go back to the WARN() thing.
> 
> I don't really have strong opinion on this, but someone should pick the 
> poison from the two options above; I tried in the mentioned commit, but 
> apparently not to general satisfaction :)

Hmm, or we can actually make the whole thing behave the way that was 
introduced by 55537871e only in case of 
sysctl_hardlockup_all_cpu_backtrace being set, and use WARN() otherwise.

I'll send out a patch for this during / after the weekend if noone else 
beats me to do it.

-- 
Jiri Kosina
SUSE Labs