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

[Felipe Contreras]

On Mon, Oct 19, 2009 at 5:57 PM, Jiri Kosina <jkosina@xxxxxxx> wrote:
> 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@xxxxxxxxx>
>> >> ---
>> >> Âipc/msg.c | Â Â2 +-
>> >> Â1 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,
>> >> Â Â Â Â Â Â Â Â Â Â Âstruct msqid_ds __user *buf, int version)
>> >> Â{
>> >> Â Â Â struct kern_ipc_perm *ipcp;
>> >> - Â Â struct msqid64_ds msqid64;
>> >> + Â Â struct msqid64_ds uninitialized_var(msqid64);
>> >> Â Â Â struct msg_queue *msq;
>> >> Â Â Â 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?

If it's a gcc bug, yes.

> 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.

The other possibility is that the bug was in gcc 4.1/4.3, and now 4.4
finds an actual problem in the code. I will try to dig deeper to see
what's actually happening... at first glance I don't see who is
initializing msqid64.

-- 
Felipe Contreras
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