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Commit 767f509c authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Thomas Gleixner
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futex: Enhance comments in futex_lock_pi() for blocking paths 



... serves a bit better to clarify between blocking
and non-blocking code paths.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <darren@dvhart.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Link: http://lkml.kernel.org/r/1435645562-975-2-git-send-email-dave@stgolabs.net


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 0e06e5be

kernel/futex.c

+9 −2
Original line number Diff line number Diff line
@@ -2268,8 +2268,11 @@ static long futex_wait_restart(struct restart_block *restart) 
/*

 * Userspace tried a 0 -> TID atomic transition of the futex value

 * and failed. The kernel side here does the whole locking operation:

 * if there are waiters then it will block, it does PI, etc. (Due to

 * races the kernel might see a 0 value of the futex too.)

 * if there are waiters then it will block as a consequence of relying

 * on rt-mutexes, it does PI, etc. (Due to races the kernel might see

 * a 0 value of the futex too.).

 *

 * Also serves as futex trylock_pi()'ing, and due semantics.

 */

static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,

			 ktime_t *time, int trylock)
@@ -2300,6 +2303,10 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, 


	ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current, 0);

	if (unlikely(ret)) {

		/*

		 * Atomic work succeeded and we got the lock,

		 * or failed. Either way, we do _not_ block.

		 */

		switch (ret) {

		case 1:

			/* We got the lock. */