linux-kernel - Re: [PATCH/RFC] RDMA/iwpm: Fix uninitialized error code in iwpm_send

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Date:   Wed, 29 Nov 2017 09:39:36 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        Tatyana Nikolova <Tatyana.E.Nikolova@...el.com>,
        Doug Ledford <dledford@...hat.com>,
        linux-rdma <linux-rdma@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH/RFC] RDMA/iwpm: Fix uninitialized error code in iwpm_send_mapinfo()

On Wed, Nov 29, 2017 at 9:24 AM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> Hi Arnd,
>
> On Wed, Nov 29, 2017 at 9:20 AM, Arnd Bergmann <arnd@...db.de> wrote:
>> On Wed, Nov 29, 2017 at 9:10 AM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>>> On Wed, Nov 29, 2017 at 12:08 AM, Jason Gunthorpe <jgg@...pe.ca> wrote:
>>>> On Thu, Nov 16, 2017 at 11:26:04AM +0100, Geert Uytterhoeven wrote:
>>>>> With gcc-4.1.2:
>>>>>
>>>>>     drivers/infiniband/core/iwpm_util.c: In function ‘iwpm_send_mapinfo’:
>>>>>     drivers/infiniband/core/iwpm_util.c:647: warning: ‘ret’ may be used uninitialized in this function
>>>>>
>>>>> Indeed, if nl_client is not found in any of the scanned has buckets, ret
>>>>> will be used uninitialized.
>>>>>
>>>>> Preinitialize ret to zero to fix this.
>>>>
>>>> Did we come to a conclusion if we should apply this to the RMDA tree? The
>>>> patch was marked RFC..
>>>
>>> So far no one commented on what's the correct behavior in case of failure,
>>> which was the actual reason for the RFC.
>>
>> As I said above, I think initializing to -EINVAL would be better than 0 here,
>
> Sorry, I misread your comment as the -EINVAL being part of another function.
>
>> but initializing 'ret' at declaration time is appropriate here (though
>> I normally
>> try to avoid doing so, see https://rusty.ozlabs.org/?p=232)
>
> +1, but if loops are involved, you have not much choice.
> I could move the preinitialization to just before the loop?
> Would you like that?

I don't think it makes much difference in this particular case, since the
function is mostly just that loop, it's fine either way.

       Arnd