linux-kernel - Re: [PATCH] usb: gadget: uvc: fix returnvar.cocci warnings

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Date:   Wed, 23 Nov 2016 09:35:36 +0100
From:   Andrzej Pietrasiewicz <andrzej.p@...sung.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Julia Lawall <julia.lawall@...6.fr>, kbuild-all@...org,
        Felipe Balbi <balbi@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        target-devel <target-devel@...r.kernel.org>,
        Joel Becker <jlbec@...lplan.org>,
        linux-nvme@...ts.infradead.org, Christoph Hellwig <hch@....de>,
        "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
Subject: Re: [PATCH] usb: gadget: uvc: fix returnvar.cocci warnings

Hi Laurent,

Thanks for a reminder.  Please see inline.

W dniu 22.11.2016 o 18:27, Laurent Pinchart pisze:
> Hi Andrzej and Julia,
>
> Could one of you please submit a patch to fix this ?
>
> On Thursday 17 Sep 2015 13:18:04 Andrzej Pietrasiewicz wrote:
>> Hi Julia,
>>
>> W dniu 17.09.2015 o 10:57, Julia Lawall pisze:
>>> Coccinelle suggests the following patch.  But the code is curious.  Is the
>>> function expected to always return a failure value?

As a matter of fact it seems it should not return anything at all,
because...

>>
>> Thank you for catching this. The function is not expected to always
>> return a failure value. Fortunately it does not matter anyway because

...because
>> the return value of the drop_link() operation is silently ignored by

And the Documentation/filesystems/configfs/configfs.txt says here:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/filesystems/configfs/configfs.txt#n397

"When unlink(2) is called on the symbolic link, the source item is
notified via the ->drop_link() method.  Like the ->drop_item() method,
this is a void function and cannot return failure."

The ->drop_item() is indeed a void function, the ->drop_link() is
actually not. This, together with the fact that the value of ->drop_link()
is silently ignored suggests, that it is the ->drop_link() return
type that should be corrected and changed to void.

@Joel: What is your opinion? Should return type be changed to void?
Is there any reason why it should still be declared int?

I'm sending a copy of this mail to target-devel and linux-nvme,
because other potentially affected users of configfs live there.

AP