linux-kernel - Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function

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Message-ID: <20081227095019.GA8248@elte.hu>
Date:	Sat, 27 Dec 2008 10:50:19 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	David Howells <dhowells@...hat.com>
Cc:	Sam Ravnborg <sam@...nborg.org>, Yinghai Lu <yinghai@...nel.org>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	mel@....ul.ie
Subject: Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333
	smp_call_function_mask


* David Howells <dhowells@...hat.com> wrote:

> Sam Ravnborg <sam@...nborg.org> wrote:
> 
> > I recall David Howells had a similar issue with the bootparamter patch set.
> > The workaround he used was to add a barrier(); call in the weak function
> > to avoid the inline.
> 
> Yes I did.  Rusty's solution was just to move the default weak functions into
> different files.
> 
> Attempting to use the noinline attribute does not work.
> 
> Of course, you could just stick the functions into lib/ in separate .c 
> files and dispense with the weak attribute altogether.

the weak functions should be close to where the code that uses them is - 
not somewhere separate (where no-one will really be aware of their 
existence). So either we find a way to avoid such repeat bugs in the 
future, or we do away with weak functions altogether and go back to 
stone-age #ifdefs ;-)

I think we should get a Sparse check that detects empty void __weak 
functions?

	Ingo
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