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Commit a60fba30 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Greg Kroah-Hartman
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UPSTREAM: futex: Provide and use pi_state_update_owner() 



commit c5cade200ab9a2a3be9e7f32a752c8d86b502ec7 upstream

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 avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c5cade200ab9a2a3be9e7f32a752c8d86b502ec7)
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
Change-Id: I17a67806a035338a55b27eea673d707fc4d8c529
parent 97500641

kernel/futex.c

+33 −33
Original line number Diff line number Diff line
@@ -858,6 +858,29 @@ 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);

	}

}



static void get_pi_state(struct futex_pi_state *pi_state)

{

	WARN_ON_ONCE(!refcount_inc_not_zero(&pi_state->refcount));
@@ -1615,26 +1638,15 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_ 
			ret = -EINVAL;

	}



	if (ret)

		goto out_unlock;



	if (!ret) {

		/*

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

	 * going back and subsequent operations must not fail.

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

		 * there is no going back and subsequent operations must

		 * not fail.

		 */



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

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

	list_del_init(&pi_state->list);

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



	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);



		pi_state_update_owner(pi_state, new_owner);

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

	}



out_unlock:

	raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
@@ -2570,19 +2582,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, 
	 * We fixed up user space. Now we need to fix the pi_state

	 * itself.

	 */

	if (pi_state->owner != NULL) {

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

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

		list_del_init(&pi_state->list);

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

	}



	pi_state->owner = newowner;



	raw_spin_lock(&newowner->pi_lock);

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

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

	raw_spin_unlock(&newowner->pi_lock);

	pi_state_update_owner(pi_state, newowner);

	raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);



	return argowner == current;