From: David Daney <ddaney@caviumnetworks.com>
To: Jean Delvare <khali@linux-fr.org>
Cc: David Daney <david.s.daney@gmail.com>,
"Justin P. Mattock" <justinmattock@gmail.com>,
linux-kernel@vger.kernel.org, reiserfs-devel@vger.kernel.org,
linux-bluetooth@vger.kernel.org, clemens@ladisch.de,
debora@linux.vnet.ibm.com, dri-devel@lists.freedesktop.org,
linux-i2c@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
linux-media@vger.kernel.org
Subject: Re: [PATCH 6/8]i2c:i2c_core Fix warning: variable 'dummy' set but not used
Date: Tue, 15 Jun 2010 09:20:39 -0700 [thread overview]
Message-ID: <4C17A857.8030306@caviumnetworks.com> (raw)
In-Reply-To: <20100615134039.6ccfc17a@hyperion.delvare>
On 06/15/2010 04:40 AM, Jean Delvare wrote:
> Hi David,
>
> On Mon, 14 Jun 2010 14:28:57 -0700, David Daney wrote:
>> On 06/14/2010 01:53 PM, Jean Delvare wrote:
>>> Hi Justin,
>>>
>>> On Mon, 14 Jun 2010 13:26:46 -0700, Justin P. Mattock wrote:
>>>> could be a right solution, could be wrong
>>>> here is the warning:
>>>> CC drivers/i2c/i2c-core.o
>>>> drivers/i2c/i2c-core.c: In function 'i2c_register_adapter':
>>>> drivers/i2c/i2c-core.c:757:15: warning: variable 'dummy' set but not used
>>>>
>>>> Signed-off-by: Justin P. Mattock<justinmattock@gmail.com>
>>>>
>>>> ---
>>>> drivers/i2c/i2c-core.c | 2 ++
>>>> 1 files changed, 2 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>>> index 1cca263..79c6c26 100644
>>>> --- a/drivers/i2c/i2c-core.c
>>>> +++ b/drivers/i2c/i2c-core.c
>>>> @@ -794,6 +794,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>>>> mutex_lock(&core_lock);
>>>> dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
>>>> __process_new_adapter);
>>>> + if(!dummy)
>>>> + dummy = 0;
>>>
>>> One word: scripts/checkpatch.pl
>>>
>>> In other news, the above is just plain wrong. First we force people to
>>> read the result of bus_for_each_drv() and then when they do and don't
>>> need the value, gcc complains, so we add one more layer of useless
>>> code, which developers and possibly tools will later wonder and
>>> complain about? I can easily imagine that a static code analyzer would
>>> spot the above code as being a potential bug.
>>>
>>> Let's stop this madness now please.
>>>
>>> Either __must_check goes away from bus_for_each_drv() and from every
>>> other function which raises this problem, or we must disable that new
>>> type of warning gcc 4.6.0 generates. Depends which warnings we value
>>> more, as we can't sanely have both.
>>>
>>
>> That is the crux of the whole thing. Putting in crap to get rid of the
>> __must_check warning someone obviously wanted to provoke is just plain
>> wrong.
>
> __process_new_adapter() calls i2c_do_add_adapter() which always returns
> 0. Why should I check the return value of bus_for_each_drv() when I
> know it will always be 0 by construction?
>
> Also note that the same function is also called through
> bus_for_each_dev() somewhere else in i2c-core, and there is no warning
> there because bus_for_each_dev() is not marked __must_check. How
> consistent is this? If bus_for_each_dev() is OK without __must_check,
> then I can't see why bus_for_each_drv() wouldn't be.
>
Well, I would advocate removing the __must_check then.
David Daney
next prev parent reply other threads:[~2010-06-15 16:20 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-14 20:26 [PATCH 0/8] Fix gcc 4.6.0 set but not used warning messages Justin P. Mattock
2010-06-14 20:26 ` [PATCH 1/8]reiserfs:stree.c Fix variable set but not used Justin P. Mattock
2010-06-14 20:48 ` Nick Bowler
2010-06-14 21:09 ` Justin P. Mattock
2010-06-14 21:05 ` Edward Shishkin
2010-06-14 21:21 ` Justin P. Mattock
2010-06-14 21:47 ` Edward Shishkin
2010-06-14 22:50 ` Justin P. Mattock
2010-06-14 23:07 ` Stefan Richter
2010-06-15 0:01 ` Justin P. Mattock
2010-06-14 20:26 ` [PATCH 2/8]bluetooth/hci_ldisc.c Fix warning: variable 'tty' " Justin P. Mattock
2010-06-15 0:24 ` Gustavo F. Padovan
2010-06-14 20:26 ` [PATCH 3/8]char/hpet.c Fix variable 'hpet' " Justin P. Mattock
2010-06-14 20:26 ` [PATCH 4/8]drivers:tmp.c Fix warning: variable 'rc' " Justin P. Mattock
2010-06-15 0:13 ` Valdis.Kletnieks
2010-06-15 2:12 ` Justin P. Mattock
2010-06-15 3:49 ` Valdis.Kletnieks
2010-06-15 3:56 ` Justin P. Mattock
2010-06-15 5:29 ` Peter Stuge
2010-06-15 5:58 ` Justin P. Mattock
2010-06-15 6:57 ` Stefan Richter
2010-06-15 7:27 ` Justin P. Mattock
2010-06-15 7:56 ` Stefan Richter
2010-06-15 8:30 ` Justin P. Mattock
2010-06-15 9:19 ` Jean Delvare
2010-06-15 9:41 ` Justin P. Mattock
2010-06-15 18:53 ` Sergey V.
2010-06-15 19:36 ` Justin P. Mattock
2010-06-14 20:26 ` [PATCH 5/8]drm:drm_gem Fix warning: variable 'dev' " Justin P. Mattock
2010-06-14 20:26 ` [PATCH 6/8]i2c:i2c_core Fix warning: variable 'dummy' " Justin P. Mattock
2010-06-14 20:53 ` Jean Delvare
2010-06-14 21:06 ` Justin P. Mattock
2010-06-15 11:43 ` Jean Delvare
2010-06-15 16:51 ` Justin P. Mattock
2010-06-14 21:28 ` David Daney
2010-06-15 11:40 ` Jean Delvare
2010-06-15 16:20 ` David Daney [this message]
2010-06-16 9:45 ` Jean Delvare
2010-06-14 20:26 ` [PATCH 7/8]ieee1394/sdp2 Fix warning: variable 'unit_characteristics' " Justin P. Mattock
2010-06-14 21:44 ` [PATCH] ieee1394: sbp2: remove unused code Stefan Richter
2010-06-14 22:35 ` Justin P. Mattock
2010-06-14 23:22 ` Stefan Richter
2010-06-14 23:58 ` Justin P. Mattock
2010-06-15 0:08 ` (no subject) Stefan Richter
2010-06-15 0:00 ` [PATCH] ieee1394: remove unused variables Stefan Richter
2010-06-15 0:05 ` [PATCH] ieee1394: sbp2: remove unused code Stefan Richter
2010-06-15 1:59 ` Justin P. Mattock
2010-06-15 11:38 ` [PATCH 7/8]ieee1394/sdp2 Fix warning: variable 'unit_characteristics' set but not used Jean Delvare
2010-06-15 16:52 ` Justin P. Mattock
2010-06-14 20:26 ` [PATCH 8/8]tuners:tuner-simple Fix warning: variable 'tun' " Justin P. Mattock
2010-06-15 5:16 ` Mauro Carvalho Chehab
2010-06-15 5:37 ` Justin P. Mattock
2010-06-15 5:50 ` Justin P. Mattock
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