The patch titled futex: futex_wait_requeue_pi commentary corrections has been added to the -mm tree. Its filename is futex-futex_wait_requeue_pi-commentary-corrections.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: futex: futex_wait_requeue_pi commentary corrections From: Darren Hart <dvhltc@xxxxxxxxxx> The state machine described in the comments wasn't updated with a follow-on fix. Address that and cleanup the corresponding commentary in the function. Signed-off-by: Darren Hart <dvhltc@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/futex.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff -puN kernel/futex.c~futex-futex_wait_requeue_pi-commentary-corrections kernel/futex.c --- a/kernel/futex.c~futex-futex_wait_requeue_pi-commentary-corrections +++ a/kernel/futex.c @@ -2102,11 +2102,11 @@ int handle_early_requeue_pi_wakeup(struc * We call schedule in futex_wait_queue_me() when we enqueue and return there * via the following: * 1) wakeup on uaddr2 after an atomic lock acquisition by futex_requeue() - * 2) wakeup on uaddr2 after a requeue and subsequent unlock - * 3) signal (before or after requeue) - * 4) timeout (before or after requeue) + * 2) wakeup on uaddr2 after a requeue + * 3) signal + * 4) timeout * - * If 3, we setup a restart_block with futex_wait_requeue_pi() as the function. + * If 3, cleanup and return -ERESTARTNOINTR. * * If 2, we may then block on trying to take the rt_mutex and return via: * 5) successful lock @@ -2114,7 +2114,7 @@ int handle_early_requeue_pi_wakeup(struc * 7) timeout * 8) other lock acquisition failure * - * If 6, we setup a restart_block with futex_lock_pi() as the function. + * If 6, return -EWOULDBLOCK (restarting the syscall would do the same). * * If 4 or 7, we cleanup and return with -ETIMEDOUT. * @@ -2232,14 +2232,11 @@ static int futex_wait_requeue_pi(u32 __u rt_mutex_unlock(pi_mutex); } else if (ret == -EINTR) { /* - * We've already been requeued, but we have no way to - * restart by calling futex_lock_pi() directly. We - * could restart the syscall, but that will look at - * the user space value and return right away. So we - * drop back with EWOULDBLOCK to tell user space that - * "val" has been changed. That's the same what the - * restart of the syscall would do in - * futex_wait_setup(). + * We've already been requeued, but cannot restart by calling + * futex_lock_pi() directly. We could restart this syscall, but + * it would detect that the user space "val" changed and return + * -EWOULDBLOCK. Save the overhead of the restart and return + * -EWOULDBLOCK directly. */ ret = -EWOULDBLOCK; } _ Patches currently in -mm which might be from dvhltc@xxxxxxxxxx are linux-next.patch futex-futex_wait_requeue_pi-commentary-corrections.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html