[PATCH] futex: PI state locking fix

21778867 · Ingo Molnar <[email protected]> · 2007-03-16 13:38:31 -08:00

Testing of -rt by IBM uncovered a locking bug in wake_futex_pi(): the PI
state needs to be locked before we access it.

Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Cc: Chuck Ebbert <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 21778867b1c8e0feb567addb6dc0a7e2ca6ecdec
Parents: d3a7b6df

Changes

1 files changed · +2 −0

File	Status	Add	Del	Content
kernel/futex.c	modified	+2	−0	View file

kernel/futex.c

View file

diff --git a/kernel/futex.c b/kernel/futex.c
index e749e7d..5a270b5 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -565,6 +565,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
 	if (!pi_state)
 		return -EINVAL;
 
+	spin_lock(&pi_state->pi_mutex.wait_lock);
 	new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
 
 	/*
@@ -604,6 +605,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
 	pi_state->owner = new_owner;
 	spin_unlock_irq(&new_owner->pi_lock);
 
+	spin_unlock(&pi_state->pi_mutex.wait_lock);
 	rt_mutex_unlock(&pi_state->pi_mutex);
 
 	return 0;