68  * lock->owner state tracking:
70  * lock->owner holds the task_struct pointer of the owner. Bit 0
73  * owner	bit0
81  * possible when bit 0 of lock->owner is 0.
85  * we need to set the bit0 before looking at the lock, and the owner may be
90  * To prevent a cmpxchg of the owner releasing the lock, we need to
95 rt_mutex_owner_encode(struct rt_mutex_base *lock, struct task_struct *owner)  in rt_mutex_owner_encode()  argument
97 	unsigned long val = (unsigned long)owner;  in rt_mutex_owner_encode()
106 rt_mutex_set_owner(struct rt_mutex_base *lock, struct task_struct *owner)  in rt_mutex_set_owner()  argument
110 	 * for a new lock owner so WRITE_ONCE is insufficient.  in rt_mutex_set_owner()
112 	xchg_acquire(&lock->owner, rt_mutex_owner_encode(lock, owner));  in rt_mutex_set_owner()
118 	WRITE_ONCE(lock->owner, rt_mutex_owner_encode(lock, NULL));  in rt_mutex_clear_owner()
123 	lock->owner = (struct task_struct *)  in clear_rt_mutex_waiters()
124 			((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);  in clear_rt_mutex_waiters()
130 	unsigned long owner, *p = (unsigned long *) &lock->owner;  in fixup_rt_mutex_waiters()  local
137 	 * lock->owner still has the waiters bit set, otherwise the  in fixup_rt_mutex_waiters()
141 	 * l->owner=T1  in fixup_rt_mutex_waiters()
144 	 *		l->owner = T1 | HAS_WAITERS;  in fixup_rt_mutex_waiters()
152 	 *				l->owner = T1 | HAS_WAITERS;  in fixup_rt_mutex_waiters()
170 	 *		    l->owner = owner  in fixup_rt_mutex_waiters()
171 	 *		    owner = l->owner & ~HAS_WAITERS;  in fixup_rt_mutex_waiters()
172 	 *		      ==> l->owner = T1  in fixup_rt_mutex_waiters()
177 	 *				    owner = l->owner & ~HAS_WAITERS;  in fixup_rt_mutex_waiters()
178 	 * cmpxchg(l->owner, T1, NULL)  in fixup_rt_mutex_waiters()
179 	 *  ===> Success (l->owner = NULL)  in fixup_rt_mutex_waiters()
181 	 *				    l->owner = owner  in fixup_rt_mutex_waiters()
182 	 *				      ==> l->owner = T1  in fixup_rt_mutex_waiters()
188 	 * bit. If the bit is set then nothing can change l->owner either  in fixup_rt_mutex_waiters()
193 	owner = READ_ONCE(*p);  in fixup_rt_mutex_waiters()
194 	if (owner & RT_MUTEX_HAS_WAITERS) {  in fixup_rt_mutex_waiters()
197 		 * why xchg_acquire() is used for updating owner for  in fixup_rt_mutex_waiters()
205 			xchg_acquire(p, owner & ~RT_MUTEX_HAS_WAITERS);  in fixup_rt_mutex_waiters()
207 			WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS);  in fixup_rt_mutex_waiters()
220 	return try_cmpxchg_acquire(&lock->owner, &old, new);  in rt_mutex_cmpxchg_acquire()
232 	return try_cmpxchg_release(&lock->owner, &old, new);  in rt_mutex_cmpxchg_release()
242 	unsigned long *p = (unsigned long *) &lock->owner;  in mark_rt_mutex_waiters()
243 	unsigned long owner, new;  in mark_rt_mutex_waiters()  local
245 	owner = READ_ONCE(*p);  in mark_rt_mutex_waiters()
247 		new = owner | RT_MUTEX_HAS_WAITERS;  in mark_rt_mutex_waiters()
248 	} while (!try_cmpxchg_relaxed(p, &owner, new));  in mark_rt_mutex_waiters()
268 	struct task_struct *owner = rt_mutex_owner(lock);  in unlock_rt_mutex_safe()  local
278 	 * cmpxchg(p, owner, 0) == owner  in unlock_rt_mutex_safe()
287 	 * cmpxchg(p, owner, 0) != owner  in unlock_rt_mutex_safe()
296 	return rt_mutex_cmpxchg_release(lock, owner, NULL);  in unlock_rt_mutex_safe()
331 	lock->owner = (struct task_struct *)  in mark_rt_mutex_waiters()
332 			((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);  in mark_rt_mutex_waiters()
336  * Simple slow path only version: lock->owner is protected by lock->wait_lock.
342 	lock->owner = NULL;  in unlock_rt_mutex_safe()
608  * @task:	the task owning the mutex (owner) for which a chain walk is
614  * @next_lock:	the mutex on which the owner of @orig_lock was blocked before
618  *		its priority to the mutex owner (can be NULL in the case
620  *		actually deboosting the owner)
663  * [10]	  task = owner(lock);			[L]
672  * Where P1 is the blocking task and P2 is the lock owner; going up one step
673  * the owner becomes the next blocked task etc..
752 	 * the previous owner of the lock might have released the lock.  in rt_mutex_adjust_prio_chain()
893 		 * If there is no owner of the lock, end of chain.  in rt_mutex_adjust_prio_chain()
900 		/* [10] Grab the next task, i.e. owner of @lock */  in rt_mutex_adjust_prio_chain()
907 		 * [12] Store whether owner is blocked  in rt_mutex_adjust_prio_chain()
920 		/* If owner is not blocked, end of chain. */  in rt_mutex_adjust_prio_chain()
953 	 * taking the owner task in [10].  in rt_mutex_adjust_prio_chain()
964 	 * We must abort the chain walk if there is no lock owner even  in rt_mutex_adjust_prio_chain()
982 	 * [10] Grab the next task, i.e. the owner of @lock  in rt_mutex_adjust_prio_chain()
984 	 * Per holding lock->wait_lock and checking for !owner above, there  in rt_mutex_adjust_prio_chain()
985 	 * must be an owner and it cannot go away.  in rt_mutex_adjust_prio_chain()
995 		 * in the owner tasks pi waiters tree with this waiter  in rt_mutex_adjust_prio_chain()
996 		 * and adjust the priority of the owner.  in rt_mutex_adjust_prio_chain()
1007 		 * the owner tasks pi waiters tree with the new top  in rt_mutex_adjust_prio_chain()
1009 		 * of the owner.  in rt_mutex_adjust_prio_chain()
1093 	 * RT_MUTEX_HAS_WAITERS bit in @lock->owner. This forces all  in try_to_take_rt_mutex()
1100 	 * - There is a lock owner. The caller must fixup the  in try_to_take_rt_mutex()
1111 	 * If @lock has an owner, give up.  in try_to_take_rt_mutex()
1177 	 * Finish the lock acquisition. @task is the new owner. If  in try_to_take_rt_mutex()
1209 	struct task_struct *owner = rt_mutex_owner(lock);  in task_blocks_on_rt_mutex()  local
1228 	if (owner == task && !(build_ww_mutex() && ww_ctx))  in task_blocks_on_rt_mutex()
1261 	if (!owner)  in task_blocks_on_rt_mutex()
1264 	raw_spin_lock(&owner->pi_lock);  in task_blocks_on_rt_mutex()
1266 		rt_mutex_dequeue_pi(owner, top_waiter);  in task_blocks_on_rt_mutex()
1267 		rt_mutex_enqueue_pi(owner, waiter);  in task_blocks_on_rt_mutex()
1269 		rt_mutex_adjust_prio(lock, owner);  in task_blocks_on_rt_mutex()
1270 		if (owner->pi_blocked_on)  in task_blocks_on_rt_mutex()
1276 	/* Store the lock on which owner is blocked or NULL */  in task_blocks_on_rt_mutex()
1277 	next_lock = task_blocked_on_lock(owner);  in task_blocks_on_rt_mutex()
1279 	raw_spin_unlock(&owner->pi_lock);  in task_blocks_on_rt_mutex()
1281 	 * Even if full deadlock detection is on, if the owner is not  in task_blocks_on_rt_mutex()
1289 	 * The owner can't disappear while holding a lock,  in task_blocks_on_rt_mutex()
1290 	 * so the owner struct is protected by wait_lock.  in task_blocks_on_rt_mutex()
1293 	get_task_struct(owner);  in task_blocks_on_rt_mutex()
1297 	res = rt_mutex_adjust_prio_chain(owner, chwalk, lock,  in task_blocks_on_rt_mutex()
1340 	lock->owner = (void *) RT_MUTEX_HAS_WAITERS;  in mark_wakeup_next_waiter()
1379 	 * If the lock already has an owner we fail to get the lock.  in rt_mutex_slowtrylock()
1387 	 * The mutex has currently no owner. Lock the wait lock and try to  in rt_mutex_slowtrylock()
1422 	 * have no waiters queued we cannot set owner to NULL here  in rt_mutex_slowunlock()
1425 	 * foo->lock->owner = NULL;  in rt_mutex_slowunlock()
1438 	 *	owner = rt_mutex_owner(lock);  in rt_mutex_slowunlock()
1441 	 *	if (cmpxchg(&lock->owner, owner, 0) == owner)  in rt_mutex_slowunlock()
1446 	 * lock->owner is serialized by lock->wait_lock:  in rt_mutex_slowunlock()
1448 	 *	lock->owner = NULL;  in rt_mutex_slowunlock()
1482 				  struct task_struct *owner)  in rtmutex_spin_on_owner()  argument
1488 		/* If owner changed, trylock again. */  in rtmutex_spin_on_owner()
1489 		if (owner != rt_mutex_owner(lock))  in rtmutex_spin_on_owner()
1492 		 * Ensure that @owner is dereferenced after checking that  in rtmutex_spin_on_owner()
1493 		 * the lock owner still matches @owner. If that fails,  in rtmutex_spin_on_owner()
1494 		 * @owner might point to freed memory. If it still matches,  in rtmutex_spin_on_owner()
1500 		 *  - the lock owner has been scheduled out  in rtmutex_spin_on_owner()
1504 		 *  - the VCPU on which owner runs is preempted  in rtmutex_spin_on_owner()
1506 		if (!owner_on_cpu(owner) || need_resched() ||  in rtmutex_spin_on_owner()
1519 				  struct task_struct *owner)  in rtmutex_spin_on_owner()  argument
1542 	struct task_struct *owner = rt_mutex_owner(lock);  in remove_waiter()  local
1554 	 * waiter of the lock and there is an owner to update.  in remove_waiter()
1556 	if (!owner || !is_top_waiter)  in remove_waiter()
1559 	raw_spin_lock(&owner->pi_lock);  in remove_waiter()
1561 	rt_mutex_dequeue_pi(owner, waiter);  in remove_waiter()
1564 		rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));  in remove_waiter()
1566 	rt_mutex_adjust_prio(lock, owner);  in remove_waiter()
1568 	/* Store the lock on which owner is blocked or NULL */  in remove_waiter()
1569 	next_lock = task_blocked_on_lock(owner);  in remove_waiter()
1571 	raw_spin_unlock(&owner->pi_lock);  in remove_waiter()
1574 	 * Don't walk the chain, if the owner task is not blocked  in remove_waiter()
1581 	get_task_struct(owner);  in remove_waiter()
1585 	rt_mutex_adjust_prio_chain(owner, RT_MUTEX_MIN_CHAINWALK, lock,  in remove_waiter()
1612 	struct task_struct *owner;  in rt_mutex_slowlock_block()  local
1636 			owner = rt_mutex_owner(lock);  in rt_mutex_slowlock_block()
1638 			owner = NULL;  in rt_mutex_slowlock_block()
1641 		if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner))  in rt_mutex_slowlock_block()
1823 	struct task_struct *owner;  in rtlock_slowlock_locked()  local
1845 			owner = rt_mutex_owner(lock);  in rtlock_slowlock_locked()
1847 			owner = NULL;  in rtlock_slowlock_locked()
1850 		if (!owner || !rtmutex_spin_on_owner(lock, &waiter, owner))  in rtlock_slowlock_locked()