1 files changed, 6 insertions, 5 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index b766d28accd6..3184d3b9cadf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1781,13 +1781,14 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
          *
          * The basic logical guarantee of a futex is that it blocks ONLY
          * if cond(var) is known to be true at the time of blocking, for
-         * any cond.  If we queued after testing *uaddr, that would open
-         * a race condition where we could block indefinitely with
+         * any cond.  If we locked the hash-bucket after testing *uaddr, that
+         * would open a race condition where we could block indefinitely with
          * cond(var) false, which would violate the guarantee.
          *
-         * A consequence is that futex_wait() can return zero and absorb
-         * a wakeup when *uaddr != val on entry to the syscall.  This is
-         * rare, but normal.
+         * On the other hand, we insert q and release the hash-bucket only
+         * after testing *uaddr.  This guarantees that futex_wait() will NOT
+         * absorb a wakeup if *uaddr does not match the desired values
+         * while the syscall executes.
          */
 retry:
         ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key);