Messages in this thread Patch in this message | | | Date | Thu, 23 Jun 2016 11:28:21 -0700 | From | Darren Hart <> | Subject | Re: futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op |
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On Thu, Jun 23, 2016 at 07:26:52PM +0200, Thomas Gleixner wrote: > On Thu, 23 Jun 2016, Darren Hart wrote: > > On Thu, Jun 23, 2016 at 03:40:36PM +0200, Thomas Gleixner wrote: > > In my opinion, we should treat the timeout value as relative for FUTEX_WAIT > > regardless of the CLOCK used. > > Which requires even more changes as you have to select which clock you are > using for adding the base time.
Right, something like the following?
diff --git a/kernel/futex.c b/kernel/futex.c index 33664f7..c39d807 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3230,8 +3230,12 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, return -EINVAL; t = timespec_to_ktime(ts); - if (cmd == FUTEX_WAIT) - t = ktime_add_safe(ktime_get(), t); + if (cmd == FUTEX_WAIT) { + if (cmd & FUTEX_CLOCK_REALTIME) + t = ktime_add_safe(ktime_get_real(), t); + else + t = ktime_add_safe(ktime_get(), t); + } tp = &t; } /* And as a follow-on, what is the reason for FUTEX_LOCK_PI only using CLOCK_REALTIME? It seems reasonable to me that a user may want to wait a specific amount of time, regardless of wall time.
-- Darren Hart Intel Open Source Technology Center
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