| From | Jiri Slaby <> | Subject | [PATCH 3.12 139/142] futex: Drop refcount if requeue_pi() acquired the rtmutex | Date | Wed, 24 Feb 2016 11:05:34 +0100 |
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From: Thomas Gleixner <tglx@linutronix.de>
3.12-stable review patch. If anyone has any objections, please let me know.
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commit fb75a4282d0d9a3c7c44d940582c2d226cf3acfb upstream.
If the proxy lock in the requeue loop acquires the rtmutex for a waiter then it acquired also refcount on the pi_state related to the futex, but the waiter side does not drop the reference count.
Add the missing free_pi_state() call.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Darren Hart <darren@dvhart.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Bhuvanesh_Surachari@mentor.com Cc: Andy Lowe <Andy_Lowe@mentor.com> Link: http://lkml.kernel.org/r/20151219200607.178132067@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- kernel/futex.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/kernel/futex.c b/kernel/futex.c index 3ee1b3ce78df..509bdd404414 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2497,6 +2497,11 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, if (q.pi_state && (q.pi_state->owner != current)) { spin_lock(q.lock_ptr); ret = fixup_pi_state_owner(uaddr2, &q, current); + /* + * Drop the reference to the pi state which + * the requeue_pi() code acquired for us. + */ + free_pi_state(q.pi_state); spin_unlock(q.lock_ptr); } } else { -- 2.7.1
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