From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Theodore Tso <tytso@mit.edu>
Subject: [patch] futex: PI state locking fix
Date: Mon, 12 Mar 2007 10:13:42 +0100 [thread overview]
Message-ID: <20070312091342.GA27425@elte.hu> (raw)
Subject: [patch] futex: PI state locking fix
From: Ingo Molnar <mingo@elte.hu>
testing of -rt by IBM uncovered a locking bug in wake_futex_pi(): the PI
state needs to be locked before we access it.
this patch has been tested in -rt. Must-have for v2.6.21.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--
kernel/futex.c | 2 ++
1 file changed, 2 insertions(+)
Index: linux/kernel/futex.c
===================================================================
--- linux.orig/kernel/futex.c
+++ linux/kernel/futex.c
@@ -566,6 +566,7 @@ static int wake_futex_pi(u32 __user *uad
if (!pi_state)
return -EINVAL;
+ spin_lock(&pi_state->pi_mutex.wait_lock);
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
/*
@@ -605,6 +606,7 @@ static int wake_futex_pi(u32 __user *uad
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;
next reply other threads:[~2007-03-12 9:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-12 9:13 Ingo Molnar [this message]
2007-03-12 9:28 ` [patch] futex: PI state locking fix Thomas Gleixner
2007-03-12 14:44 ` Chuck Ebbert
2007-03-12 14:45 ` Ingo Molnar
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