linux-kernel - Re: [PATCH] HID: hiddev: fix returned errno code in hiddev

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Date:	Sat, 03 Oct 2015 22:34:41 +0100
From:	Luis de Bethencourt <luisbg@....samsung.com>
To:	Jiri Kosina <jikos@...nel.org>
CC:	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-input@...r.kernel.org
Subject: Re: [PATCH] HID: hiddev: fix returned errno code in hiddev_connect()

On 30/09/15 20:40, Jiri Kosina wrote:
> On Wed, 30 Sep 2015, Luis de Bethencourt wrote:
> 
>> The driver is using -1 instead of the -ENOMEM defined macro to specify
>> that a buffer allocation failed. Since the error number is propagated,
>> the caller will get a -EPERM which is the wrong error condition.
> 
> Generally I agree that the more specific errno, the better.
> 
> But I am not really sure where you are seeing the bug (mapping to -EPERM) 
> in this case? I think the only caller of hiddev_connect() should be 
> hid_connect(), and the only thing that guy cares about whether individual 
> callbacks succeed or fail, so that it sets hdev->clamed flags accordingly.
> 
> Could you please be more specific about the -EPERM mapping you are talking 
> about?
> 
> Thanks,
> 

I agree with you. The only caller of hiddev_connect() only checks if the
callback succeded. It checks if the return < 0.
What I meant is that -1 means -EPERM. [0]

This patch is purely about the correctness of using -ENOMEM. The word
"propagated" was not the best way to describe this problem. I could edit
the commit message if you would like.

Thanks for the review,
Luis

[0] http://lxr.free-electrons.com/source/include/uapi/asm-generic/errno-base.h#L15
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