Lines Matching +full:use +full:- +full:rtm
1 // SPDX-License-Identifier: GPL-2.0-only
3 * RT-Mutexes: simple blocking mutual exclusion locks with PI support
7 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 * Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
17 * See Documentation/locking/rt-mutex-design.rst for details.
33 # define ww_container_of(rtm) NULL argument
61 # define ww_container_of(rtm) container_of(rtm, struct ww_mutex, base) argument
66 * lock->owner state tracking:
68 * lock->owner holds the task_struct pointer of the owner. Bit 0
79 * possible when bit 0 of lock->owner is 0.
82 * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
107 * lock->wait_lock is held but explicit acquire semantics are needed in rt_mutex_set_owner()
110 xchg_acquire(&lock->owner, rt_mutex_owner_encode(lock, owner)); in rt_mutex_set_owner()
115 /* lock->wait_lock is held so the unlock provides release semantics. */ in rt_mutex_clear_owner()
116 WRITE_ONCE(lock->owner, rt_mutex_owner_encode(lock, NULL)); in rt_mutex_clear_owner()
121 lock->owner = (struct task_struct *) in clear_rt_mutex_waiters()
122 ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); in clear_rt_mutex_waiters()
128 unsigned long owner, *p = (unsigned long *) &lock->owner; in fixup_rt_mutex_waiters()
135 * lock->owner still has the waiters bit set, otherwise the in fixup_rt_mutex_waiters()
139 * l->owner=T1 in fixup_rt_mutex_waiters()
141 * lock(l->lock) in fixup_rt_mutex_waiters()
142 * l->owner = T1 | HAS_WAITERS; in fixup_rt_mutex_waiters()
145 * unlock(l->lock) in fixup_rt_mutex_waiters()
149 * lock(l->lock) in fixup_rt_mutex_waiters()
150 * l->owner = T1 | HAS_WAITERS; in fixup_rt_mutex_waiters()
153 * unlock(l->lock) in fixup_rt_mutex_waiters()
155 * signal(->T2) signal(->T3) in fixup_rt_mutex_waiters()
156 * lock(l->lock) in fixup_rt_mutex_waiters()
159 * unlock(l->lock) in fixup_rt_mutex_waiters()
160 * lock(l->lock) in fixup_rt_mutex_waiters()
164 * unlock(l->lock) in fixup_rt_mutex_waiters()
165 * lock(l->lock) in fixup_rt_mutex_waiters()
168 * l->owner = owner in fixup_rt_mutex_waiters()
169 * owner = l->owner & ~HAS_WAITERS; in fixup_rt_mutex_waiters()
170 * ==> l->owner = T1 in fixup_rt_mutex_waiters()
172 * lock(l->lock) in fixup_rt_mutex_waiters()
175 * owner = l->owner & ~HAS_WAITERS; in fixup_rt_mutex_waiters()
176 * cmpxchg(l->owner, T1, NULL) in fixup_rt_mutex_waiters()
177 * ===> Success (l->owner = NULL) in fixup_rt_mutex_waiters()
179 * l->owner = owner in fixup_rt_mutex_waiters()
180 * ==> l->owner = T1 in fixup_rt_mutex_waiters()
185 * serialized by l->lock, so nothing else can modify the waiters in fixup_rt_mutex_waiters()
186 * bit. If the bit is set then nothing can change l->owner either in fixup_rt_mutex_waiters()
218 return try_cmpxchg_acquire(&lock->owner, &old, new); in rt_mutex_cmpxchg_acquire()
230 return try_cmpxchg_release(&lock->owner, &old, new); in rt_mutex_cmpxchg_release()
234 * Callers must hold the ->wait_lock -- which is the whole purpose as we force
240 unsigned long *p = (unsigned long *) &lock->owner; in mark_rt_mutex_waiters()
249 * The cmpxchg loop above is relaxed to avoid back-to-back ACQUIRE in mark_rt_mutex_waiters()
259 * 2) Drop lock->wait_lock
264 __releases(lock->wait_lock) in unlock_rt_mutex_safe()
269 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in unlock_rt_mutex_safe()
315 * acquire a non-contended rtmutex. in rt_mutex_try_acquire()
329 lock->owner = (struct task_struct *) in mark_rt_mutex_waiters()
330 ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS); in mark_rt_mutex_waiters()
334 * Simple slow path only version: lock->owner is protected by lock->wait_lock.
338 __releases(lock->wait_lock) in unlock_rt_mutex_safe()
340 lock->owner = NULL; in unlock_rt_mutex_safe()
341 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in unlock_rt_mutex_safe()
348 int prio = task->prio; in __waiter_prio()
357 * Update the waiter->tree copy of the sort keys.
362 lockdep_assert_held(&waiter->lock->wait_lock); in waiter_update_prio()
363 lockdep_assert(RB_EMPTY_NODE(&waiter->tree.entry)); in waiter_update_prio()
365 waiter->tree.prio = __waiter_prio(task); in waiter_update_prio()
366 waiter->tree.deadline = task->dl.deadline; in waiter_update_prio()
370 * Update the waiter->pi_tree copy of the sort keys (from the tree copy).
375 lockdep_assert_held(&waiter->lock->wait_lock); in waiter_clone_prio()
376 lockdep_assert_held(&task->pi_lock); in waiter_clone_prio()
377 lockdep_assert(RB_EMPTY_NODE(&waiter->pi_tree.entry)); in waiter_clone_prio()
379 waiter->pi_tree.prio = waiter->tree.prio; in waiter_clone_prio()
380 waiter->pi_tree.deadline = waiter->tree.deadline; in waiter_clone_prio()
384 * Only use with rt_waiter_node_{less,equal}()
387 &(struct rt_waiter_node){ .prio = __waiter_prio(p), .deadline = (p)->dl.deadline }
394 if (left->prio < right->prio) in rt_waiter_node_less()
403 if (dl_prio(left->prio)) in rt_waiter_node_less()
404 return dl_time_before(left->deadline, right->deadline); in rt_waiter_node_less()
412 if (left->prio != right->prio) in rt_waiter_node_equal()
421 if (dl_prio(left->prio)) in rt_waiter_node_equal()
422 return left->deadline == right->deadline; in rt_waiter_node_equal()
430 if (rt_waiter_node_less(&waiter->tree, &top_waiter->tree)) in rt_mutex_steal()
438 if (rt_or_dl_prio(waiter->tree.prio)) in rt_mutex_steal()
441 return rt_waiter_node_equal(&waiter->tree, &top_waiter->tree); in rt_mutex_steal()
455 if (rt_waiter_node_less(&aw->tree, &bw->tree)) in __waiter_less()
461 if (rt_waiter_node_less(&bw->tree, &aw->tree)) in __waiter_less()
464 /* NOTE: relies on waiter->ww_ctx being set before insertion */ in __waiter_less()
465 if (aw->ww_ctx) { in __waiter_less()
466 if (!bw->ww_ctx) in __waiter_less()
469 return (signed long)(aw->ww_ctx->stamp - in __waiter_less()
470 bw->ww_ctx->stamp) < 0; in __waiter_less()
479 lockdep_assert_held(&lock->wait_lock); in rt_mutex_enqueue()
481 rb_add_cached(&waiter->tree.entry, &lock->waiters, __waiter_less); in rt_mutex_enqueue()
487 lockdep_assert_held(&lock->wait_lock); in rt_mutex_dequeue()
489 if (RB_EMPTY_NODE(&waiter->tree.entry)) in rt_mutex_dequeue()
492 rb_erase_cached(&waiter->tree.entry, &lock->waiters); in rt_mutex_dequeue()
493 RB_CLEAR_NODE(&waiter->tree.entry); in rt_mutex_dequeue()
507 lockdep_assert_held(&task->pi_lock); in rt_mutex_enqueue_pi()
509 rb_add_cached(&waiter->pi_tree.entry, &task->pi_waiters, __pi_waiter_less); in rt_mutex_enqueue_pi()
515 lockdep_assert_held(&task->pi_lock); in rt_mutex_dequeue_pi()
517 if (RB_EMPTY_NODE(&waiter->pi_tree.entry)) in rt_mutex_dequeue_pi()
520 rb_erase_cached(&waiter->pi_tree.entry, &task->pi_waiters); in rt_mutex_dequeue_pi()
521 RB_CLEAR_NODE(&waiter->pi_tree.entry); in rt_mutex_dequeue_pi()
529 lockdep_assert_held(&lock->wait_lock); in rt_mutex_adjust_prio()
531 lockdep_assert_held(&p->pi_lock); in rt_mutex_adjust_prio()
534 pi_task = task_top_pi_waiter(p)->task; in rt_mutex_adjust_prio()
546 WARN_ON_ONCE(wqh->rtlock_task); in rt_mutex_wake_q_add_task()
548 wqh->rtlock_task = task; in rt_mutex_wake_q_add_task()
550 wake_q_add(&wqh->head, task); in rt_mutex_wake_q_add_task()
557 rt_mutex_wake_q_add_task(wqh, w->task, w->wake_state); in rt_mutex_wake_q_add()
562 if (IS_ENABLED(CONFIG_PREEMPT_RT) && wqh->rtlock_task) { in rt_mutex_wake_up_q()
563 wake_up_state(wqh->rtlock_task, TASK_RTLOCK_WAIT); in rt_mutex_wake_up_q()
564 put_task_struct(wqh->rtlock_task); in rt_mutex_wake_up_q()
565 wqh->rtlock_task = NULL; in rt_mutex_wake_up_q()
568 if (!wake_q_empty(&wqh->head)) in rt_mutex_wake_up_q()
569 wake_up_q(&wqh->head); in rt_mutex_wake_up_q()
599 return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL; in task_blocked_on_lock()
604 * Decreases task's usage by one - may thus free the task.
621 * Returns 0 or -EDEADLK.
626 * [Pn] task->pi_lock held
627 * [L] rtmutex->wait_lock held
631 * rtmutex->wait_lock
632 * task->pi_lock
648 * [1] lock(task->pi_lock); [R] acquire [P1]
649 * [2] waiter = task->pi_blocked_on; [P1]
651 * [4] lock = waiter->lock; [P1]
652 * [5] if (!try_lock(lock->wait_lock)) { [P1] try to acquire [L]
653 * unlock(task->pi_lock); release [P1]
658 * [8] unlock(task->pi_lock); release [P1]
663 * lock(task->pi_lock); [L] acquire [P2]
666 * [13] unlock(task->pi_lock); release [P2]
667 * unlock(lock->wait_lock); release [L]
712 top_task->comm, task_pid_nr(top_task)); in rt_mutex_adjust_prio_chain()
716 return -EDEADLK; in rt_mutex_adjust_prio_chain()
729 raw_spin_lock_irq(&task->pi_lock); in rt_mutex_adjust_prio_chain()
734 waiter = task->pi_blocked_on; in rt_mutex_adjust_prio_chain()
737 * [3] check_exit_conditions_1() protected by task->pi_lock. in rt_mutex_adjust_prio_chain()
764 if (next_lock != waiter->lock) in rt_mutex_adjust_prio_chain()
775 * P3 should not return -EDEADLK because it gets trapped in the cycle in rt_mutex_adjust_prio_chain()
776 * created by P1 and P2 (which will resolve -- and runs into in rt_mutex_adjust_prio_chain()
789 if (IS_ENABLED(CONFIG_PREEMPT_RT) && waiter->ww_ctx && detect_deadlock) in rt_mutex_adjust_prio_chain()
821 if (rt_waiter_node_equal(&waiter->tree, task_to_waiter_node(task))) { in rt_mutex_adjust_prio_chain()
829 * [4] Get the next lock; per holding task->pi_lock we can't unblock in rt_mutex_adjust_prio_chain()
832 lock = waiter->lock; in rt_mutex_adjust_prio_chain()
834 * [5] We need to trylock here as we are holding task->pi_lock, in rt_mutex_adjust_prio_chain()
838 * Per the above, holding task->pi_lock guarantees lock exists, so in rt_mutex_adjust_prio_chain()
839 * inverting this lock order is infeasible from a life-time in rt_mutex_adjust_prio_chain()
842 if (!raw_spin_trylock(&lock->wait_lock)) { in rt_mutex_adjust_prio_chain()
843 raw_spin_unlock_irq(&task->pi_lock); in rt_mutex_adjust_prio_chain()
849 * [6] check_exit_conditions_2() protected by task->pi_lock and in rt_mutex_adjust_prio_chain()
850 * lock->wait_lock. in rt_mutex_adjust_prio_chain()
858 ret = -EDEADLK; in rt_mutex_adjust_prio_chain()
863 * logic pick which of the contending threads gets -EDEADLK. in rt_mutex_adjust_prio_chain()
869 if (IS_ENABLED(CONFIG_PREEMPT_RT) && orig_waiter && orig_waiter->ww_ctx) in rt_mutex_adjust_prio_chain()
872 raw_spin_unlock(&lock->wait_lock); in rt_mutex_adjust_prio_chain()
886 raw_spin_unlock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
890 * [9] check_exit_conditions_3 protected by lock->wait_lock. in rt_mutex_adjust_prio_chain()
894 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_adjust_prio_chain()
900 raw_spin_lock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
915 raw_spin_unlock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
916 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_adjust_prio_chain()
953 * Since we hold lock->waiter_lock, task cannot unblock, even if we in rt_mutex_adjust_prio_chain()
954 * release task->pi_lock. in rt_mutex_adjust_prio_chain()
956 raw_spin_unlock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
960 * [9] check_exit_conditions_3 protected by lock->wait_lock. in rt_mutex_adjust_prio_chain()
974 wake_up_state(top_waiter->task, top_waiter->wake_state); in rt_mutex_adjust_prio_chain()
975 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_adjust_prio_chain()
982 * Per holding lock->wait_lock and checking for !owner above, there in rt_mutex_adjust_prio_chain()
986 raw_spin_lock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
1025 * [12] check_exit_conditions_4() protected by task->pi_lock in rt_mutex_adjust_prio_chain()
1026 * and lock->wait_lock. The actual decisions are made after we in rt_mutex_adjust_prio_chain()
1032 * task->pi_lock next_lock cannot be dereferenced anymore. in rt_mutex_adjust_prio_chain()
1042 raw_spin_unlock(&task->pi_lock); in rt_mutex_adjust_prio_chain()
1043 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_adjust_prio_chain()
1066 raw_spin_unlock_irq(&task->pi_lock); in rt_mutex_adjust_prio_chain()
1074 * Try to take an rt-mutex
1076 * Must be called with lock->wait_lock held and interrupts disabled
1087 lockdep_assert_held(&lock->wait_lock); in try_to_take_rt_mutex()
1091 * RT_MUTEX_HAS_WAITERS bit in @lock->owner. This forces all in try_to_take_rt_mutex()
1093 * and they serialize on @lock->wait_lock. in try_to_take_rt_mutex()
1098 * - There is a lock owner. The caller must fixup the in try_to_take_rt_mutex()
1102 * - @task acquires the lock and there are no other in try_to_take_rt_mutex()
1141 * the lock. @task->pi_blocked_on is NULL, so it does in try_to_take_rt_mutex()
1158 * pi_lock dance.@task->pi_blocked_on is NULL in try_to_take_rt_mutex()
1167 * Clear @task->pi_blocked_on. Requires protection by in try_to_take_rt_mutex()
1168 * @task->pi_lock. Redundant operation for the @waiter == NULL in try_to_take_rt_mutex()
1172 raw_spin_lock(&task->pi_lock); in try_to_take_rt_mutex()
1173 task->pi_blocked_on = NULL; in try_to_take_rt_mutex()
1177 * waiter into @task->pi_waiters tree. in try_to_take_rt_mutex()
1181 raw_spin_unlock(&task->pi_lock); in try_to_take_rt_mutex()
1198 * This must be called with lock->wait_lock held and interrupts disabled
1211 lockdep_assert_held(&lock->wait_lock); in task_blocks_on_rt_mutex()
1218 * the other will detect the deadlock and return -EDEADLOCK, in task_blocks_on_rt_mutex()
1226 return -EDEADLK; in task_blocks_on_rt_mutex()
1228 raw_spin_lock(&task->pi_lock); in task_blocks_on_rt_mutex()
1229 waiter->task = task; in task_blocks_on_rt_mutex()
1230 waiter->lock = lock; in task_blocks_on_rt_mutex()
1239 task->pi_blocked_on = waiter; in task_blocks_on_rt_mutex()
1241 raw_spin_unlock(&task->pi_lock); in task_blocks_on_rt_mutex()
1244 struct rt_mutex *rtm; in task_blocks_on_rt_mutex() local
1247 rtm = container_of(lock, struct rt_mutex, rtmutex); in task_blocks_on_rt_mutex()
1248 res = __ww_mutex_add_waiter(waiter, rtm, ww_ctx); in task_blocks_on_rt_mutex()
1250 raw_spin_lock(&task->pi_lock); in task_blocks_on_rt_mutex()
1252 task->pi_blocked_on = NULL; in task_blocks_on_rt_mutex()
1253 raw_spin_unlock(&task->pi_lock); in task_blocks_on_rt_mutex()
1261 raw_spin_lock(&owner->pi_lock); in task_blocks_on_rt_mutex()
1267 if (owner->pi_blocked_on) in task_blocks_on_rt_mutex()
1276 raw_spin_unlock(&owner->pi_lock); in task_blocks_on_rt_mutex()
1292 raw_spin_unlock_irq(&lock->wait_lock); in task_blocks_on_rt_mutex()
1297 raw_spin_lock_irq(&lock->wait_lock); in task_blocks_on_rt_mutex()
1306 * Called with lock->wait_lock held and interrupts disabled.
1313 lockdep_assert_held(&lock->wait_lock); in mark_wakeup_next_waiter()
1315 raw_spin_lock(¤t->pi_lock); in mark_wakeup_next_waiter()
1320 * Remove it from current->pi_waiters and deboost. in mark_wakeup_next_waiter()
1323 * rt_mutex_setprio() to update p->pi_top_task before the in mark_wakeup_next_waiter()
1337 lock->owner = (void *) RT_MUTEX_HAS_WAITERS; in mark_wakeup_next_waiter()
1342 * p->pi_top_task pointer points to a blocked task). This however can in mark_wakeup_next_waiter()
1351 raw_spin_unlock(¤t->pi_lock); in mark_wakeup_next_waiter()
1368 * Slow path try-lock function:
1377 * This can be done without taking the @lock->wait_lock as in rt_mutex_slowtrylock()
1385 * acquire the lock. We use irqsave here to support early boot calls. in rt_mutex_slowtrylock()
1387 raw_spin_lock_irqsave(&lock->wait_lock, flags); in rt_mutex_slowtrylock()
1391 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in rt_mutex_slowtrylock()
1405 * Slow path to release a rt-mutex.
1413 raw_spin_lock_irqsave(&lock->wait_lock, flags); in rt_mutex_slowunlock()
1422 * foo->lock->owner = NULL; in rt_mutex_slowunlock()
1423 * rtmutex_lock(foo->lock); <- fast path in rt_mutex_slowunlock()
1424 * free = atomic_dec_and_test(foo->refcnt); in rt_mutex_slowunlock()
1425 * rtmutex_unlock(foo->lock); <- fast path in rt_mutex_slowunlock()
1428 * raw_spin_unlock(foo->lock->wait_lock); in rt_mutex_slowunlock()
1433 * lock->wait_lock. So we do the following sequence: in rt_mutex_slowunlock()
1437 * raw_spin_unlock(&lock->wait_lock); in rt_mutex_slowunlock()
1438 * if (cmpxchg(&lock->owner, owner, 0) == owner) in rt_mutex_slowunlock()
1443 * lock->owner is serialized by lock->wait_lock: in rt_mutex_slowunlock()
1445 * lock->owner = NULL; in rt_mutex_slowunlock()
1446 * raw_spin_unlock(&lock->wait_lock); in rt_mutex_slowunlock()
1449 /* Drops lock->wait_lock ! */ in rt_mutex_slowunlock()
1453 raw_spin_lock_irqsave(&lock->wait_lock, flags); in rt_mutex_slowunlock()
1463 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in rt_mutex_slowunlock()
1497 * - the lock owner has been scheduled out in rtmutex_spin_on_owner()
1498 * - current is not longer the top waiter in rtmutex_spin_on_owner()
1499 * - current is requested to reschedule (redundant in rtmutex_spin_on_owner()
1501 * - the VCPU on which owner runs is preempted in rtmutex_spin_on_owner()
1525 * - rtmutex, futex on all kernels
1526 * - mutex and rwsem substitutions on RT kernels
1532 * Must be called with lock->wait_lock held and interrupts disabled. It must
1542 lockdep_assert_held(&lock->wait_lock); in remove_waiter()
1544 raw_spin_lock(¤t->pi_lock); in remove_waiter()
1546 current->pi_blocked_on = NULL; in remove_waiter()
1547 raw_spin_unlock(¤t->pi_lock); in remove_waiter()
1556 raw_spin_lock(&owner->pi_lock); in remove_waiter()
1568 raw_spin_unlock(&owner->pi_lock); in remove_waiter()
1580 raw_spin_unlock_irq(&lock->wait_lock); in remove_waiter()
1585 raw_spin_lock_irq(&lock->wait_lock); in remove_waiter()
1589 * rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
1594 * @timeout: the pre-initialized and started timer, or NULL for none
1595 * @waiter: the pre-initialized rt_mutex_waiter
1597 * Must be called with lock->wait_lock held and interrupts disabled
1605 struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex); in rt_mutex_slowlock_block() local
1614 if (timeout && !timeout->task) { in rt_mutex_slowlock_block()
1615 ret = -ETIMEDOUT; in rt_mutex_slowlock_block()
1619 ret = -EINTR; in rt_mutex_slowlock_block()
1624 ret = __ww_mutex_check_kill(rtm, waiter, ww_ctx); in rt_mutex_slowlock_block()
1633 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_slowlock_block()
1638 raw_spin_lock_irq(&lock->wait_lock); in rt_mutex_slowlock_block()
1651 * If the result is not -EDEADLOCK or the caller requested in rt_mutex_handle_deadlock()
1654 if (res != -EDEADLOCK || detect_deadlock) in rt_mutex_handle_deadlock()
1657 if (build_ww_mutex() && w->ww_ctx) in rt_mutex_handle_deadlock()
1660 raw_spin_unlock_irq(&lock->wait_lock); in rt_mutex_handle_deadlock()
1671 * __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
1684 struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex); in __rt_mutex_slowlock() local
1685 struct ww_mutex *ww = ww_container_of(rtm); in __rt_mutex_slowlock()
1688 lockdep_assert_held(&lock->wait_lock); in __rt_mutex_slowlock()
1693 __ww_mutex_check_waiters(rtm, ww_ctx); in __rt_mutex_slowlock()
1710 if (!ww_ctx->is_wait_die) in __rt_mutex_slowlock()
1711 __ww_mutex_check_waiters(rtm, ww_ctx); in __rt_mutex_slowlock()
1749 * rt_mutex_slowlock - Locking slowpath invoked when fast path fails
1762 * Do all pre-schedule work here, before we queue a waiter and invoke in rt_mutex_slowlock()
1763 * PI -- any such work that trips on rtlock (PREEMPT_RT spinlock) would in rt_mutex_slowlock()
1771 * Technically we could use raw_spin_[un]lock_irq() here, but this can in rt_mutex_slowlock()
1774 * rtmutex with lock->wait_lock held. But we cannot unconditionally in rt_mutex_slowlock()
1775 * enable interrupts in that early boot case. So we need to use the in rt_mutex_slowlock()
1778 raw_spin_lock_irqsave(&lock->wait_lock, flags); in rt_mutex_slowlock()
1780 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in rt_mutex_slowlock()
1789 lockdep_assert(!current->pi_blocked_on); in __rt_mutex_lock()
1804 * rtlock_slowlock_locked - Slow path lock acquisition for RT locks
1812 lockdep_assert_held(&lock->wait_lock); in rtlock_slowlock_locked()
1835 raw_spin_unlock_irq(&lock->wait_lock); in rtlock_slowlock_locked()
1840 raw_spin_lock_irq(&lock->wait_lock); in rtlock_slowlock_locked()
1861 raw_spin_lock_irqsave(&lock->wait_lock, flags); in rtlock_slowlock()
1863 raw_spin_unlock_irqrestore(&lock->wait_lock, flags); in rtlock_slowlock()