linux-kernel - Re: [PATCH] kernel/sched/core.c: need return NULL when BUG() is defined as empty.

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Date:	Thu, 23 May 2013 09:00:45 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Russell King - ARM Linux <linux@....linux.org.uk>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] kernel/sched/core.c: need return NULL when BUG() is defined
 as empty.

On 05/23/2013 12:19 AM, Peter Zijlstra wrote:
> On Wed, May 22, 2013 at 02:33:17PM +0100, Russell King - ARM Linux wrote:
>> > On Wed, May 22, 2013 at 11:11:56AM +0200, Peter Zijlstra wrote:
>>> > > On Mon, May 20, 2013 at 03:48:53PM +0800, Chen Gang wrote:
>>>> > > > 
>>>> > > > When neither CONFIG_BUG nor HAVE_ARCH_BUG is defined, need let function
>>>> > > > return failure value ('NULL') instead of random value.
>>> > > 
>>> > > What will such a kernel do? Happily continue running whenever we hit a
>>> > > BUG? that seems like a particularly bad idea. Should we not have a stub
>>> > > BUG() function like:
>>> > > 
>>> > > void BUG(void) __attribute__((noreturn))
>>> > > {
>>> > > 	local_irq_disable();
>>> > > 	while (1) ;
>>> > > }
>> > 
>> > Eww.  So you've a platform where you have things like panic_on_oops
>> > enabled, and you hit this bug... do we really want to just stop?
>> > Wouldn't replacing BUG() with panic("BUG"); be better ?
>> > 
>> > But, this begs the question - what is the point of being able to turn
>> > off BUG() ?  As BUG() on any sensible architecture is implemented by
>> > placing the minimum of code at the callsite (eg, one instruction if
>> > not using verbose) anything like the above is likely to be bigger.
>> > 
>> > So, I'd actually argue that rather than trying to "fix" this, get rid
>> > of CONFIG_BUG and make it always enabled everywhere - just like what
>> > has recently been done with hotplug.
> Works for me. 
> 

Thanks all, I should send the related patch for it.

Excuse me, I have to do another things, so I will finish it within this
week (2013-05-26)

Welcome any additional suggestions and completions.


Thanks.
-- 
Chen Gang

Asianux Corporation
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