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Message-ID: <20100604101848.GA6367@a1.tnic>
Date: Fri, 4 Jun 2010 12:18:48 +0200
From: Borislav Petkov <bp@...en8.de>
To: Al Viro <viro@...IV.linux.org.uk>
Cc: Changli Gao <xiaosuo@...il.com>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] fs: optimize mpage_readpage()
From: Al Viro <viro@...IV.linux.org.uk>
Date: Fri, Jun 04, 2010 at 09:30:31AM +0100
> On Fri, Jun 04, 2010 at 10:13:22AM +0200, Borislav Petkov wrote:
> > > > > - bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
> > > > > + bio = do_mpage_readpage(NULL, page, 1, &last_block_in_bio,
>
> > Right, the uninitialized warning above happens when you remove the NULL
> > assignment, i.e.
> >
> > struct bio *bio;
> >
> > ...
> >
> > bio = do_mpage_readpage(bio, ...)
>
> WTF? His patch does *NOT* leave you with bio = do_mpage_readpage(bio, ...),
> it replaces that with bio = do_mpage_readpage(NULL, ...).
>
> Which variant has produced a warning?
>
> > But(!), in the mpage_readpage(), bio _absolutely_ has to be NULL because
> > it is checked if being so later in do_mpage_readpage(), so this one is a
> > complete different story.
> >
> > To cut a long story short, you're correct, gcc is b0rked when warning
> > about passing addresses of variables to functions which only write to
> > them.
>
> To make it even shorter, you've misapplied the patch. Correct?
Yes.
--
Regards/Gruss,
Boris.
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