Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 34c8e1c2 authored by Lee Jones's avatar Lee Jones Committed by Greg Kroah-Hartman
Browse files

futex: Provide and use pi_state_update_owner() 



From: Thomas Gleixner <tglx@linutronix.de>

[ Upstream commit c5cade200ab9a2a3be9e7f32a752c8d86b502ec7 ]

Updating pi_state::owner is done at several places with the same
code. Provide a function for it and use that at the obvious places.

This is also a preparation for a bug fix to avoid yet another copy of the
same code or alternatively introducing a completely unpenetratable mess of
gotos.

Originally-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3edf5f2a

kernel/futex.c

+33 −31
Original line number Diff line number Diff line
@@ -835,6 +835,29 @@ static struct futex_pi_state * alloc_pi_state(void) 
	return pi_state;

}



static void pi_state_update_owner(struct futex_pi_state *pi_state,

				  struct task_struct *new_owner)

{

	struct task_struct *old_owner = pi_state->owner;



	lockdep_assert_held(&pi_state->pi_mutex.wait_lock);



	if (old_owner) {

		raw_spin_lock(&old_owner->pi_lock);

		WARN_ON(list_empty(&pi_state->list));

		list_del_init(&pi_state->list);

		raw_spin_unlock(&old_owner->pi_lock);

	}



	if (new_owner) {

		raw_spin_lock(&new_owner->pi_lock);

		WARN_ON(!list_empty(&pi_state->list));

		list_add(&pi_state->list, &new_owner->pi_state_list);

		pi_state->owner = new_owner;

		raw_spin_unlock(&new_owner->pi_lock);

	}

}



/*

 * Must be called with the hb lock held.

 */
@@ -1427,26 +1450,16 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this, 
		else

			ret = -EINVAL;

	}

	if (ret) {

		raw_spin_unlock(&pi_state->pi_mutex.wait_lock);

		return ret;

	}



	raw_spin_lock_irq(&pi_state->owner->pi_lock);

	WARN_ON(list_empty(&pi_state->list));

	list_del_init(&pi_state->list);

	raw_spin_unlock_irq(&pi_state->owner->pi_lock);



	raw_spin_lock_irq(&new_owner->pi_lock);

	WARN_ON(!list_empty(&pi_state->list));

	list_add(&pi_state->list, &new_owner->pi_state_list);

	pi_state->owner = new_owner;

	raw_spin_unlock_irq(&new_owner->pi_lock);



	if (!ret) {

		/*

	 * We've updated the uservalue, this unlock cannot fail.

		 * This is a point of no return; once we modified the uval

		 * there is no going back and subsequent operations must

		 * not fail.

		 */

		pi_state_update_owner(pi_state, new_owner);

		deboost = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);

	}



	raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);

	spin_unlock(&hb->lock);
@@ -2318,19 +2331,8 @@ retry: 
	 * We fixed up user space. Now we need to fix the pi_state

	 * itself.

	 */

	if (pi_state->owner != NULL) {

		raw_spin_lock_irq(&pi_state->owner->pi_lock);

		WARN_ON(list_empty(&pi_state->list));

		list_del_init(&pi_state->list);

		raw_spin_unlock_irq(&pi_state->owner->pi_lock);

	}

	pi_state_update_owner(pi_state, newowner);



	pi_state->owner = newowner;



	raw_spin_lock_irq(&newowner->pi_lock);

	WARN_ON(!list_empty(&pi_state->list));

	list_add(&pi_state->list, &newowner->pi_state_list);

	raw_spin_unlock_irq(&newowner->pi_lock);

	return 0;



	/*