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

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Message-ID: <20130702180447.GB16282@quack.suse.cz>
Date:	Tue, 2 Jul 2013 20:04:47 +0200
From:	Jan Kara <jack@...e.cz>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	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 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.

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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