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    SubjectRe: [tip PATCH v6 6/8] RFC: futex: Add FUTEX_HAS_TIMEOUT flag to restart.futex.flags
    Darren Hart a écrit :
    > Currently restart is only used if there is a timeout. The requeue_pi
    > functionality requires restarting to futex_lock_pi() on signal after
    > wakeup in futex_wait_requeue_pi() regardless of if there was a timeout
    > or not. Using 0 for the timeout value is confusing as that could
    > indicate an expired timer. The flag makes this explicit.
    >
    > Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Sripathi Kodi <sripathik@in.ibm.com>
    > Cc: Peter Zijlstra <peterz@infradead.org>
    > Cc: John Stultz <johnstul@us.ibm.com>
    > Cc: Steven Rostedt <rostedt@goodmis.org>
    > Cc: Dinakar Guniguntala <dino@in.ibm.com>
    > Cc: Ulrich Drepper <drepper@redhat.com>
    > Cc: Eric Dumazet <dada1@cosmosbay.com>
    > Cc: Ingo Molnar <mingo@elte.hu>
    > Cc: Jakub Jelinek <jakub@redhat.com>
    > ---
    >
    > kernel/futex.c | 12 ++++++++----
    > 1 files changed, 8 insertions(+), 4 deletions(-)
    >
    > diff --git a/kernel/futex.c b/kernel/futex.c
    > index dd05803..f54faf5 100644
    > --- a/kernel/futex.c
    > +++ b/kernel/futex.c
    > @@ -1254,6 +1254,7 @@ handle_fault:
    > */
    > #define FLAGS_SHARED 0x01
    > #define FLAGS_CLOCKRT 0x02
    > +#define FLAGS_HAS_TIMEOUT 0x04
    >
    > static long futex_wait_restart(struct restart_block *restart);
    >
    > @@ -1493,7 +1494,7 @@ retry_private:
    > restart->futex.val = val;
    > restart->futex.time = abs_time->tv64;
    > restart->futex.bitset = bitset;
    > - restart->futex.flags = 0;
    > + restart->futex.flags = FLAGS_HAS_TIMEOUT;
    >
    > if (fshared)
    > restart->futex.flags |= FLAGS_SHARED;
    > @@ -1517,13 +1518,16 @@ static long futex_wait_restart(struct restart_block *restart)
    > {
    > u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
    > int fshared = 0;
    > - ktime_t t;
    > + ktime_t t, *tp = NULL;
    >
    > - t.tv64 = restart->futex.time;
    > + if (restart->futex.flags | FLAGS_HAS_TIMEOUT) {

    You probably meant :

    if (restart->futex.flags & FLAGS_HAS_TIMEOUT)

    > + t.tv64 = restart->futex.time;
    > + tp = &t;
    > + }
    > restart->fn = do_no_restart_syscall;
    > if (restart->futex.flags & FLAGS_SHARED)
    > fshared = 1;
    > - return (long)futex_wait(uaddr, fshared, restart->futex.val, &t,
    > + return (long)futex_wait(uaddr, fshared, restart->futex.val, tp,
    > restart->futex.bitset,
    > restart->futex.flags & FLAGS_CLOCKRT);
    > }
    >
    >


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