linux-kernel - Re: [PATCH] Bluetooth: Pre-initialize variables in read_local_oob_ext_data

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Message-Id: <0F69C638-5050-4603-A3FE-12FD8E9B27DD@holtmann.org>
Date:	Wed, 13 May 2015 23:11:56 +0200
From:	Marcel Holtmann <marcel@...tmann.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	"Gustavo F. Padovan" <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	BlueZ development <linux-bluetooth@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Bluetooth: Pre-initialize variables in read_local_oob_ext_data_complete()

Hi Geert,

>>>>> net/bluetooth/mgmt.c: In function ‘read_local_oob_ext_data_complete’:
>>>>> net/bluetooth/mgmt.c:6474: warning: ‘r256’ may be used uninitialized in this function
>>>>> net/bluetooth/mgmt.c:6474: warning: ‘h256’ may be used uninitialized in this function
>>>>> net/bluetooth/mgmt.c:6474: warning: ‘r192’ may be used uninitialized in this function
>>>>> net/bluetooth/mgmt.c:6474: warning: ‘h192’ may be used uninitialized in this function
>>>>> 
>>>>> While these are false positives, the code can be shortened by
>>>>> pre-initializing the hash table pointers and eir_len. This has the side
>>>>> effect of killing the compiler warnings.
>>>> 
>>>> can you be a bit specific on which compiler version is this. I fixed one occurrence that seemed valid. However in this case the compiler seems to be just plain stupid. On a gcc 4.9, I am not seeing these for example.
>>> 
>>> gcc 4.1.2. As there were too many false positives, these warnings were
>>> disabled in later versions (throwing away the children with the bad water).
>>> 
>>> If you don't like my patch, just drop it. I only look at newly
>>> introduced warnings
>>> of this kind anyway.
>> 
>> I really do not know what is the best solution here. This is a false positive. And I have been looking at this particular code for a warning that was valid, but we missed initially. But these warnings that you are fixing are clearly false positive.
> 
> I only sent patches to fix false positives if I think the patches improve the
> code. As this is a subjective matter, it's up to you as the maintainer to
> decide.
> 
>> If this only happens with an old compiler version, I would tend to leave the code as is. Then again, what is the general preferred approach here?
> 
> As this is a false positive, it's clearly up to the maintainer to
> decide if the patch
> improves the code or not.

and in this case, I have no idea if I want to bother or not. I really just don’t. Since nobody else complained, I might just leave it as is since it really is a false positive.

Regards

Marcel

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