Commit 21778867 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds

[PATCH] futex: PI state locking fix

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: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Chuck Ebbert <cebbert@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d3a7b6df
......@@ -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;
......
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