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

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Message-ID: <alpine.LSU.2.20.1703290854390.26906@n3.vanv.qr>
Date:   Wed, 29 Mar 2017 08:55:15 +0200 (CEST)
From:   Jan Engelhardt <jengelh@...i.de>
To:     SIMRAN SINGHAL <singhalsimran0@...il.com>
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 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.