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Subject: Re: [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
To:     Markus Elfring <Markus.Elfring@web.de>,
        Joe Perches <joe@perches.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Anton Altaparmakov <anton@tuxera.com>,
        Andy Whitcroft <apw@canonical.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Boris Pismenny <borisp@mellanox.com>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dennis Dalessandro <dennis.dalessandro@intel.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        dri-devel@lists.freedesktop.org,
        Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>,
        =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>,
        Leon Romanovsky <leon@kernel.org>,
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        Mike Marciniszyn <mike.marciniszyn@intel.com>,
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        =?UTF-8?Q?Pali_Roh=c3=a1r?= <pali.rohar@gmail.com>,
        Rob Clark <robdclark@gmail.com>,
        Saeed Mahameed <saeedm@mellanox.com>,
        Sean Paul <sean@poorly.run>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        xen-devel@lists.xenproject.org, Enrico Weigelt <lkml@metux.net>
References: <20190829165025.15750-1-efremov@linux.com>
 <0d9345ed-f16a-de0b-6125-1f663765eb46@web.de>
From:   Denis Efremov <efremov@linux.com>
Message-ID: <689c8baf-2298-f086-3461-5cd1cdd191c6@linux.com>
Date:   Sat, 31 Aug 2019 18:54:12 +0300
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On 31.08.2019 12:15, Markus Elfring wrote:
>> +# nested likely/unlikely calls
>> +        if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) {
>> +            WARN("LIKELY_MISUSE",
> 
> How do you think about to use the specification “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)”
> in this regular expression?

Hmm, 
(?:   <- Catch group is required here, since it is used in diagnostic message,
         see $1
   IS_ERR
   (?:_ <- Another atomic group just to show that '_' is a common prefix?
           I'm not sure about this. Usually, Perl interpreter is very good at optimizing such things.
           You could see this optimization if you run perl with -Mre=debug.
     (?:OR_NULL|VALUE))?|WARN)

Regards,
Denis