linux-ext4 - Re: [GIT PULL] ext4 updates for 3.11

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Message-Id: <20130703094135.985a3130812988831f3f524a@canb.auug.org.au>
Date:	Wed, 3 Jul 2013 09:41:35 +1000
From:	Stephen Rothwell <sfr@...b.auug.org.au>
To:	Jan Kara <jack@...e.cz>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Theodore Ts'o <tytso@....edu>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] ext4 updates for 3.11

On Tue, 2 Jul 2013 20:04:47 +0200 Jan Kara <jack@...e.cz> wrote:
>
> On Tue 02-07-13 10:18:32, Linus Torvalds wrote:
> > Hmm I'm getting this compiler warning:
> > 
> >   fs/ext4/inode.c: In function ‘ext4_writepages’:
> >   fs/ext4/inode.c:2219:6: warning: ‘err’ may be used uninitialized in
> > this function [-Wmaybe-uninitialized]
> > 
> > and I think the compiler is right to warn. The 'err' variable is set
> > inside a whilte() and an if() statement, and it is not at all obvious
> > that those codepaths are always taken.
> > 
> > Maybe that "map->m_len" is always guaranteed to be nonzero, and the
> > "while()" statement could be a "do { } while()" one. But if so, make
> > it so, don't write code as if it might never be executed, when the
> > return value seems to *depend* on it being executed.
>   That's caused by my patches (only for certain gcc versions). map->m_len
> is guaranteed to be > 0 in the first iteration (the function is called from
> under if (map->m_len > 0)). I though Ted silenced that warning but
> apparently he did not. The cleanest fix is likely to make a do-while loop
> from that one. I'll send Ted a patch for that.

I did report that warning about 4 weeks ago ... and provided a fix that
was way over the top (but pointed out another problem that was fixed).

-- 
Cheers,
Stephen Rothwell                    sfr@...b.auug.org.au

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