Message-ID: <1438365622.19675.97.camel@perches.com>
Subject: Re: [PATCH 14/15] mm: Drop unlikely before IS_ERR(_OR_NULL)
From: Joe Perches <joe@perches.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: yalin wang <yalin.wang2010@gmail.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Andrew Morton <akpm@linux-foundation.org>,
        linaro-kernel@lists.linaro.org,
        open list <linux-kernel@vger.kernel.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        David Rientjes <rientjes@google.com>,
        Ebru Akagunduz <ebru.akagunduz@gmail.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
        Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>,
        Vlastimil Babka <vbabka@suse.cz>
Date: Fri, 31 Jul 2015 11:00:22 -0700
In-Reply-To: <20150731110637.GB899@linux>
References: <cover.1438331416.git.viresh.kumar@linaro.org>
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	 <20150731085646.GA31544@node.dhcp.inet.fi>
	 <FA3D9AE9-9D1E-4232-87DE-42F21B408B24@gmail.com>
	 <20150731093450.GA7505@linux> <1438338481.19675.72.camel@perches.com>
	 <20150731110637.GB899@linux>
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On Fri, 2015-07-31 at 16:36 +0530, Viresh Kumar wrote:
> On 31-07-15, 03:28, Joe Perches wrote:
> > If it's all fixed, then it's unlikely to be needed in checkpatch.
> 
> I thought checkpatch is more about not committing new mistakes, rather than
> finding them in old code.

True, but checkpatch is more about style than substance.

There are a lot of things that _could_ be added to the script
but don't have to be because of relative rarity.

The unanswered fundamental though is whether the unlikely use
in #define IS_ERR_VALUE is useful.

include/linux/err.h:21:#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

How often does using unlikely here make the code smaller/faster
with more recent compilers than gcc 3.4?  Or even using gcc 3.4.


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