futex: Fix small (and harmless looking) inconsistencies

During (post-commit) review Darren spotted a few minor things. One
(harmless AFAICT) type inconsistency and a comment that wasn't as
clear as hoped.

Reported-by: Darren Hart (VMWare) <dvhart@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/futex.c b/kernel/futex.c
index 7ac167683c9f8d7fa7608f611e16280fa0fbf697..ede2f1ef851104f214e637fe3932871df9f0b203 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1025,7 +1025,8 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
                              struct futex_pi_state **ps)
 {
        pid_t pid = uval & FUTEX_TID_MASK;
-       int ret, uval2;
+       u32 uval2;
+       int ret;
 
        /*
         * Userspace might have messed up non-PI and PI futexes [3]
@@ -1441,6 +1442,11 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
        if (ret)
                goto out_unlock;
 
+       /*
+        * This is a point of no return; once we modify the uval there is no
+        * going back and subsequent operations must not fail.
+        */
+
        raw_spin_lock(&pi_state->owner->pi_lock);
        WARN_ON(list_empty(&pi_state->list));
        list_del_init(&pi_state->list);
@@ -1452,9 +1458,6 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
        pi_state->owner = new_owner;
        raw_spin_unlock(&new_owner->pi_lock);
 
-       /*
-        * We've updated the uservalue, this unlock cannot fail.
-        */
        postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
 
 out_unlock: