linux-kernel - Re: [PATCH 2/7] ipc: fix trivial warning

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Date:	Mon, 19 Oct 2009 16:57:14 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Felipe Contreras <felipe.contreras@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: [PATCH 2/7] ipc: fix trivial warning

On Mon, 19 Oct 2009, Felipe Contreras wrote:

> >> ipc/msg.c: In function ?msgctl_down?:
> >> ipc/msg.c:415: warning: ?msqid64? may be used uninitialized in this function
> >>
> >> Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>
> >> ---
> >>  ipc/msg.c |    2 +-
> >>  1 files changed, 1 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/ipc/msg.c b/ipc/msg.c
> >> index 2ceab7f..085bd58 100644
> >> --- a/ipc/msg.c
> >> +++ b/ipc/msg.c
> >> @@ -412,7 +412,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
> >>                      struct msqid_ds __user *buf, int version)
> >>  {
> >>       struct kern_ipc_perm *ipcp;
> >> -     struct msqid64_ds msqid64;
> >> +     struct msqid64_ds uninitialized_var(msqid64);
> >>       struct msg_queue *msq;
> >>       int err;
> >
> > What gcc are you using? I am not getting any warning at least with gcc
> > "(SUSE Linux) 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision
> > 135036]"
> 
> gcc (GCC) 4.4.1 20090725 (Red Hat 4.4.1-2)
> 
> Since I moved to Fedora 11 I get more warnings than other people,
> possibly because gcc 4.4.

Wouldn't it be better just to report this to gcc developers as a bug 
instead?

I have verified both with 4.1 and 4.3, and it doesn't emit this 
false-positive warning, so there have been gcc versions getting this 
right. Ergo gcc developers should rather fix this "regression" and revert 
to the old behavior, methinks.

-- 
Jiri Kosina
SUSE Labs, Novell Inc.