Date: Fri, 18 Dec 2015 16:49:21 -0800
From: Davidlohr Bueso <dave@stgolabs.net>
To: Darren Hart <dvhart@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op
Message-ID: <20151219004921.GG17386@linux-uzut.site>
References: <9f3bdc116d79d23f5ee72ceb9a2a857f5ff8fa29.1450474525.git.dvhart@linux.intel.com>
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On Fri, 18 Dec 2015, Darren Hart wrote:

>While reviewing Michael Kerrisk's recent futex manpage update, I noticed
>that we allow the FUTEX_CLOCK_REALTIME flag for FUTEX_WAIT_BITSET but
>not for FUTEX_WAIT.
>
>FUTEX_WAIT is treated as a simple version for FUTEX_WAIT_BITSET
>internally (with a bitmask of FUTEX_BITSET_MATCH_ANY). As such, I cannot
>come up with a reason for this exclusion for FUTEX_WAIT.
>
>This change does modify the behavior of the futex syscall, changing a
>call with FUTEX_WAIT | FUTEX_CLOCK_REALTIME from returning -ENOSYS, to be
>equivalent to FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME with a bitset of
>FUTEX_BITSET_MATCH_ANY.
>
>Cc: Thomas Gleixner <tglx@linutronix.de>
>Cc: Peter Zijlstra <peterz@infradead.org>
>Cc: Davidlohr Bueso <dave@stgolabs.net>
>Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
>Signed-off-by: Darren Hart <dvhart@linux.intel.com>

Acked-by: Davidlohr Bueso <dave@stgolabs.net>
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