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

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Date:	Tue, 06 Oct 2015 09:58:54 +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 05/10/15 15:24, Jiri Kosina wrote:
> On Sat, 3 Oct 2015, Luis de Bethencourt wrote:
> 
>>> 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?
>>>
>> 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]
> 
> I still don't understand what problem you are chasing here, sorry. EPERM 
> is defined to be 1, yes. So are many other completely unrelated #defines.
> 
>> 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.
> 
> You seem to imply that someone might be interpreting that -1 as a define 
> from errno.h. But that's not the case.
> 
> Are you going to look at every 'return -1' occurence in the kernel and 
> convert it to something else? That can keep you busy for quite some time:
> 
> 	$ git grep 'return -1' | wc -l
> 	9167
> 
> The only cleanup I'd imagine at least remotely possible in this case would 
> be to convert the ->connect() callbacks return bool.
> 

This is a very good point. I will write a second version of the patch that
converts the return to a boolean.

Thanks for the review,
Luis
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