netdev - Re: [PATCH v2] netfilter: Clean up tests if NULL returned on failure

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Message-ID: <CALrZqyOMPfvt1OyH_LrNwj-a316gt=ZU2O0h+s+_NWH49dj_sw@mail.gmail.com>
Date:   Wed, 29 Mar 2017 14:45:57 +0530
From:   SIMRAN SINGHAL <singhalsimran0@...il.com>
To:     Jan Engelhardt <jengelh@...i.de>
Cc:     wensong@...ux-vs.org, Simon Horman <horms@...ge.net.au>,
        Julian Anastasov <ja@....bg>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        lvs-devel@...r.kernel.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, linux-kernel@...r.kernel.org,
        outreachy-kernel <outreachy-kernel@...glegroups.com>
Subject: Re: [PATCH v2] netfilter: Clean up tests if NULL returned on failure

On Wed, Mar 29, 2017 at 2:19 PM, SIMRAN SINGHAL
<singhalsimran0@...il.com> wrote:
> On Wed, Mar 29, 2017 at 12:25 PM, Jan Engelhardt <jengelh@...i.de> wrote:
>>
>> On Tuesday 2017-03-28 18:23, SIMRAN SINGHAL wrote:
>>>On Tue, Mar 28, 2017 at 7:24 PM, Jan Engelhardt <jengelh@...i.de> wrote:
>>>> On Tuesday 2017-03-28 15:13, simran singhal wrote:
>>>>
>>>>>Some functions like kmalloc/kzalloc return NULL on failure. When NULL
>>>>>represents failure, !x is commonly used.
>>>>>
>>>>>@@ -910,7 +910,7 @@ ip_vs_new_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest,
>>>>>       }
>>>>>
>>>>>       dest = kzalloc(sizeof(struct ip_vs_dest), GFP_KERNEL);
>>>>>-      if (dest == NULL)
>>>>>+      if (!dest)
>>>>>               return -ENOMEM;
>>>>
>>>> This kind of transformation however is not cleanup anymore, it's really
>>>> bikeshedding and should be avoided. There are pro and cons for both
>>>> variants, and there is not really an overwhelming number of arguments
>>>> for either variant to justify the change.
>>>
>>>Sorry, but I didn't get what you are trying to convey. And particularly pros and
>>>cons of both variants.
>>
>> The ==NULL/!=NULL part sort of ensures that the left side is a pointer, which
>> is lost when just using the variable and have it implicitly convert to bool.
>
> Thanks for the explaination!!!!
>
> But, according to me we should prefer != NULL over ==NULL according to
> coding style.

Sorry their is typing mistake in above.

But, according to me we should prefer !var over ( var ==NULL ) according to the
coding style