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Commit bf92cf3a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

futex: Cleanup refcounting 



Add a put_pit_state() as counterpart for get_pi_state() so the refcounting
becomes consistent.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: dvhart@infradead.org
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170322104151.801778516@infradead.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 734009e9

kernel/futex.c

+9 −4
Original line number Diff line number Diff line
@@ -812,6 +812,11 @@ static struct futex_pi_state * alloc_pi_state(void) 
	return pi_state;

}



static void get_pi_state(struct futex_pi_state *pi_state)

{

	WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount));

}



/*

 * Drops a reference to the pi_state object and frees or caches it

 * when the last reference is gone.
@@ -1103,7 +1108,7 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval, 
		goto out_einval;



out_attach:

	atomic_inc(&pi_state->refcount);

	get_pi_state(pi_state);

	raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);

	*ps = pi_state;

	return 0;
@@ -1990,7 +1995,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, 
			 * refcount on the pi_state and store the pointer in

			 * the futex_q object of the waiter.

			 */

			atomic_inc(&pi_state->refcount);

			get_pi_state(pi_state);

			this->pi_state = pi_state;

			ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,

							this->rt_waiter,