Re: [PATCH] futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op

[Davidlohr Bueso]

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@xxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
> Reported-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
> Signed-off-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>

Acked-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
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