* Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
* Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt
* Copyright (C) 2006 Esben Nielsen
+ * Adaptive Spinlocks:
+ * Copyright (C) 2008 Novell, Inc., Gregory Haskins, Sven Dietrich,
+ * and Peter Morreale,
+ * Adaptive Spinlocks simplification:
+ * Copyright (C) 2008 Red Hat, Inc., Steven Rostedt <srostedt@redhat.com>
*
* See Documentation/locking/rt-mutex-design.rst for details.
*/
-#include <linux/spinlock.h>
-#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/deadline.h>
#include <linux/sched/signal.h>
#include <linux/sched/rt.h>
-#include <linux/sched/deadline.h>
#include <linux/sched/wake_q.h>
-#include <linux/sched/debug.h>
-#include <linux/timer.h>
+#include <linux/ww_mutex.h>
#include "rtmutex_common.h"
+#ifndef WW_RT
+# define build_ww_mutex() (false)
+# define ww_container_of(rtm) NULL
+
+static inline int __ww_mutex_add_waiter(struct rt_mutex_waiter *waiter,
+ struct rt_mutex *lock,
+ struct ww_acquire_ctx *ww_ctx)
+{
+ return 0;
+}
+
+static inline void __ww_mutex_check_waiters(struct rt_mutex *lock,
+ struct ww_acquire_ctx *ww_ctx)
+{
+}
+
+static inline void ww_mutex_lock_acquired(struct ww_mutex *lock,
+ struct ww_acquire_ctx *ww_ctx)
+{
+}
+
+static inline int __ww_mutex_check_kill(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter,
+ struct ww_acquire_ctx *ww_ctx)
+{
+ return 0;
+}
+
+#else
+# define build_ww_mutex() (true)
+# define ww_container_of(rtm) container_of(rtm, struct ww_mutex, base)
+# include "ww_mutex.h"
+#endif
+
/*
* lock->owner state tracking:
*
*/
static __always_inline void
-rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
+rt_mutex_set_owner(struct rt_mutex_base *lock, struct task_struct *owner)
{
unsigned long val = (unsigned long)owner;
WRITE_ONCE(lock->owner, (struct task_struct *)val);
}
-static __always_inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void clear_rt_mutex_waiters(struct rt_mutex_base *lock)
{
lock->owner = (struct task_struct *)
((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
}
-static __always_inline void fixup_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void fixup_rt_mutex_waiters(struct rt_mutex_base *lock)
{
unsigned long owner, *p = (unsigned long *) &lock->owner;
* set up.
*/
#ifndef CONFIG_DEBUG_RT_MUTEXES
-# define rt_mutex_cmpxchg_acquire(l,c,n) (cmpxchg_acquire(&l->owner, c, n) == c)
-# define rt_mutex_cmpxchg_release(l,c,n) (cmpxchg_release(&l->owner, c, n) == c)
+static __always_inline bool rt_mutex_cmpxchg_acquire(struct rt_mutex_base *lock,
+ struct task_struct *old,
+ struct task_struct *new)
+{
+ return try_cmpxchg_acquire(&lock->owner, &old, new);
+}
+
+static __always_inline bool rt_mutex_cmpxchg_release(struct rt_mutex_base *lock,
+ struct task_struct *old,
+ struct task_struct *new)
+{
+ return try_cmpxchg_release(&lock->owner, &old, new);
+}
/*
* Callers must hold the ->wait_lock -- which is the whole purpose as we force
* all future threads that attempt to [Rmw] the lock to the slowpath. As such
* relaxed semantics suffice.
*/
-static __always_inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void mark_rt_mutex_waiters(struct rt_mutex_base *lock)
{
unsigned long owner, *p = (unsigned long *) &lock->owner;
* 2) Drop lock->wait_lock
* 3) Try to unlock the lock with cmpxchg
*/
-static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
+static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex_base *lock,
unsigned long flags)
__releases(lock->wait_lock)
{
}
#else
-# define rt_mutex_cmpxchg_acquire(l,c,n) (0)
-# define rt_mutex_cmpxchg_release(l,c,n) (0)
+static __always_inline bool rt_mutex_cmpxchg_acquire(struct rt_mutex_base *lock,
+ struct task_struct *old,
+ struct task_struct *new)
+{
+ return false;
+
+}
+
+static __always_inline bool rt_mutex_cmpxchg_release(struct rt_mutex_base *lock,
+ struct task_struct *old,
+ struct task_struct *new)
+{
+ return false;
+}
-static __always_inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+static __always_inline void mark_rt_mutex_waiters(struct rt_mutex_base *lock)
{
lock->owner = (struct task_struct *)
((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
/*
* Simple slow path only version: lock->owner is protected by lock->wait_lock.
*/
-static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
+static __always_inline bool unlock_rt_mutex_safe(struct rt_mutex_base *lock,
unsigned long flags)
__releases(lock->wait_lock)
{
}
#endif
+static __always_inline int __waiter_prio(struct task_struct *task)
+{
+ int prio = task->prio;
+
+ if (!rt_prio(prio))
+ return DEFAULT_PRIO;
+
+ return prio;
+}
+
+static __always_inline void
+waiter_update_prio(struct rt_mutex_waiter *waiter, struct task_struct *task)
+{
+ waiter->prio = __waiter_prio(task);
+ waiter->deadline = task->dl.deadline;
+}
+
/*
* Only use with rt_mutex_waiter_{less,equal}()
*/
#define task_to_waiter(p) \
- &(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
+ &(struct rt_mutex_waiter){ .prio = __waiter_prio(p), .deadline = (p)->dl.deadline }
static __always_inline int rt_mutex_waiter_less(struct rt_mutex_waiter *left,
struct rt_mutex_waiter *right)
return 1;
}
+static inline bool rt_mutex_steal(struct rt_mutex_waiter *waiter,
+ struct rt_mutex_waiter *top_waiter)
+{
+ if (rt_mutex_waiter_less(waiter, top_waiter))
+ return true;
+
+#ifdef RT_MUTEX_BUILD_SPINLOCKS
+ /*
+ * Note that RT tasks are excluded from same priority (lateral)
+ * steals to prevent the introduction of an unbounded latency.
+ */
+ if (rt_prio(waiter->prio) || dl_prio(waiter->prio))
+ return false;
+
+ return rt_mutex_waiter_equal(waiter, top_waiter);
+#else
+ return false;
+#endif
+}
+
#define __node_2_waiter(node) \
rb_entry((node), struct rt_mutex_waiter, tree_entry)
static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
{
- return rt_mutex_waiter_less(__node_2_waiter(a), __node_2_waiter(b));
+ struct rt_mutex_waiter *aw = __node_2_waiter(a);
+ struct rt_mutex_waiter *bw = __node_2_waiter(b);
+
+ if (rt_mutex_waiter_less(aw, bw))
+ return 1;
+
+ if (!build_ww_mutex())
+ return 0;
+
+ if (rt_mutex_waiter_less(bw, aw))
+ return 0;
+
+ /* NOTE: relies on waiter->ww_ctx being set before insertion */
+ if (aw->ww_ctx) {
+ if (!bw->ww_ctx)
+ return 1;
+
+ return (signed long)(aw->ww_ctx->stamp -
+ bw->ww_ctx->stamp) < 0;
+ }
+
+ return 0;
}
static __always_inline void
-rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
+rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
{
rb_add_cached(&waiter->tree_entry, &lock->waiters, __waiter_less);
}
static __always_inline void
-rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
+rt_mutex_dequeue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
{
if (RB_EMPTY_NODE(&waiter->tree_entry))
return;
rt_mutex_setprio(p, pi_task);
}
+/* RT mutex specific wake_q wrappers */
+static __always_inline void rt_mutex_wake_q_add(struct rt_wake_q_head *wqh,
+ struct rt_mutex_waiter *w)
+{
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && w->wake_state != TASK_NORMAL) {
+ if (IS_ENABLED(CONFIG_PROVE_LOCKING))
+ WARN_ON_ONCE(wqh->rtlock_task);
+ get_task_struct(w->task);
+ wqh->rtlock_task = w->task;
+ } else {
+ wake_q_add(&wqh->head, w->task);
+ }
+}
+
+static __always_inline void rt_mutex_wake_up_q(struct rt_wake_q_head *wqh)
+{
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && wqh->rtlock_task) {
+ wake_up_state(wqh->rtlock_task, TASK_RTLOCK_WAIT);
+ put_task_struct(wqh->rtlock_task);
+ wqh->rtlock_task = NULL;
+ }
+
+ if (!wake_q_empty(&wqh->head))
+ wake_up_q(&wqh->head);
+
+ /* Pairs with preempt_disable() in mark_wakeup_next_waiter() */
+ preempt_enable();
+}
+
/*
* Deadlock detection is conditional:
*
return chwalk == RT_MUTEX_FULL_CHAINWALK;
}
-/*
- * Max number of times we'll walk the boosting chain:
- */
-int max_lock_depth = 1024;
-
-static __always_inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
+static __always_inline struct rt_mutex_base *task_blocked_on_lock(struct task_struct *p)
{
return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
}
*/
static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
enum rtmutex_chainwalk chwalk,
- struct rt_mutex *orig_lock,
- struct rt_mutex *next_lock,
+ struct rt_mutex_base *orig_lock,
+ struct rt_mutex_base *next_lock,
struct rt_mutex_waiter *orig_waiter,
struct task_struct *top_task)
{
struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
struct rt_mutex_waiter *prerequeue_top_waiter;
int ret = 0, depth = 0;
- struct rt_mutex *lock;
+ struct rt_mutex_base *lock;
bool detect_deadlock;
bool requeue = true;
if (next_lock != waiter->lock)
goto out_unlock_pi;
+ /*
+ * There could be 'spurious' loops in the lock graph due to ww_mutex,
+ * consider:
+ *
+ * P1: A, ww_A, ww_B
+ * P2: ww_B, ww_A
+ * P3: A
+ *
+ * P3 should not return -EDEADLK because it gets trapped in the cycle
+ * created by P1 and P2 (which will resolve -- and runs into
+ * max_lock_depth above). Therefore disable detect_deadlock such that
+ * the below termination condition can trigger once all relevant tasks
+ * are boosted.
+ *
+ * Even when we start with ww_mutex we can disable deadlock detection,
+ * since we would supress a ww_mutex induced deadlock at [6] anyway.
+ * Supressing it here however is not sufficient since we might still
+ * hit [6] due to adjustment driven iteration.
+ *
+ * NOTE: if someone were to create a deadlock between 2 ww_classes we'd
+ * utterly fail to report it; lockdep should.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && waiter->ww_ctx && detect_deadlock)
+ detect_deadlock = false;
+
/*
* Drop out, when the task has no waiters. Note,
* top_waiter can be NULL, when we are in the deboosting
* walk, we detected a deadlock.
*/
if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
- raw_spin_unlock(&lock->wait_lock);
ret = -EDEADLK;
+
+ /*
+ * When the deadlock is due to ww_mutex; also see above. Don't
+ * report the deadlock and instead let the ww_mutex wound/die
+ * logic pick which of the contending threads gets -EDEADLK.
+ *
+ * NOTE: assumes the cycle only contains a single ww_class; any
+ * other configuration and we fail to report; also, see
+ * lockdep.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && orig_waiter && orig_waiter->ww_ctx)
+ ret = 0;
+
+ raw_spin_unlock(&lock->wait_lock);
goto out_unlock_pi;
}
* serializes all pi_waiters access and rb_erase() does not care about
* the values of the node being removed.
*/
- waiter->prio = task->prio;
- waiter->deadline = task->dl.deadline;
+ waiter_update_prio(waiter, task);
rt_mutex_enqueue(lock, waiter);
* to get the lock.
*/
if (prerequeue_top_waiter != rt_mutex_top_waiter(lock))
- wake_up_process(rt_mutex_top_waiter(lock)->task);
+ wake_up_state(waiter->task, waiter->wake_state);
raw_spin_unlock_irq(&lock->wait_lock);
return 0;
}
* callsite called task_blocked_on_lock(), otherwise NULL
*/
static int __sched
-try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
+try_to_take_rt_mutex(struct rt_mutex_base *lock, struct task_struct *task,
struct rt_mutex_waiter *waiter)
{
lockdep_assert_held(&lock->wait_lock);
* trylock attempt.
*/
if (waiter) {
- /*
- * If waiter is not the highest priority waiter of
- * @lock, give up.
- */
- if (waiter != rt_mutex_top_waiter(lock))
- return 0;
+ struct rt_mutex_waiter *top_waiter = rt_mutex_top_waiter(lock);
/*
- * We can acquire the lock. Remove the waiter from the
- * lock waiters tree.
+ * If waiter is the highest priority waiter of @lock,
+ * or allowed to steal it, take it over.
*/
- rt_mutex_dequeue(lock, waiter);
-
+ if (waiter == top_waiter || rt_mutex_steal(waiter, top_waiter)) {
+ /*
+ * We can acquire the lock. Remove the waiter from the
+ * lock waiters tree.
+ */
+ rt_mutex_dequeue(lock, waiter);
+ } else {
+ return 0;
+ }
} else {
/*
* If the lock has waiters already we check whether @task is
* not need to be dequeued.
*/
if (rt_mutex_has_waiters(lock)) {
- /*
- * If @task->prio is greater than or equal to
- * the top waiter priority (kernel view),
- * @task lost.
- */
- if (!rt_mutex_waiter_less(task_to_waiter(task),
- rt_mutex_top_waiter(lock)))
+ /* Check whether the trylock can steal it. */
+ if (!rt_mutex_steal(task_to_waiter(task),
+ rt_mutex_top_waiter(lock)))
return 0;
/*
*
* This must be called with lock->wait_lock held and interrupts disabled
*/
-static int __sched task_blocks_on_rt_mutex(struct rt_mutex *lock,
+static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task,
+ struct ww_acquire_ctx *ww_ctx,
enum rtmutex_chainwalk chwalk)
{
struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex_waiter *top_waiter = waiter;
- struct rt_mutex *next_lock;
+ struct rt_mutex_base *next_lock;
int chain_walk = 0, res;
lockdep_assert_held(&lock->wait_lock);
raw_spin_lock(&task->pi_lock);
waiter->task = task;
waiter->lock = lock;
- waiter->prio = task->prio;
- waiter->deadline = task->dl.deadline;
+ waiter_update_prio(waiter, task);
/* Get the top priority waiter on the lock */
if (rt_mutex_has_waiters(lock))
raw_spin_unlock(&task->pi_lock);
+ if (build_ww_mutex() && ww_ctx) {
+ struct rt_mutex *rtm;
+
+ /* Check whether the waiter should back out immediately */
+ rtm = container_of(lock, struct rt_mutex, rtmutex);
+ res = __ww_mutex_add_waiter(waiter, rtm, ww_ctx);
+ if (res) {
+ raw_spin_lock(&task->pi_lock);
+ rt_mutex_dequeue(lock, waiter);
+ task->pi_blocked_on = NULL;
+ raw_spin_unlock(&task->pi_lock);
+ return res;
+ }
+ }
+
if (!owner)
return 0;
*
* Called with lock->wait_lock held and interrupts disabled.
*/
-static void __sched mark_wakeup_next_waiter(struct wake_q_head *wake_q,
- struct rt_mutex *lock)
+static void __sched mark_wakeup_next_waiter(struct rt_wake_q_head *wqh,
+ struct rt_mutex_base *lock)
{
struct rt_mutex_waiter *waiter;
* deboost but before waking our donor task, hence the preempt_disable()
* before unlock.
*
- * Pairs with preempt_enable() in rt_mutex_postunlock();
+ * Pairs with preempt_enable() in rt_mutex_wake_up_q();
*/
preempt_disable();
- wake_q_add(wake_q, waiter->task);
+ rt_mutex_wake_q_add(wqh, waiter);
raw_spin_unlock(¤t->pi_lock);
}
+static int __sched __rt_mutex_slowtrylock(struct rt_mutex_base *lock)
+{
+ int ret = try_to_take_rt_mutex(lock, current, NULL);
+
+ /*
+ * try_to_take_rt_mutex() sets the lock waiters bit
+ * unconditionally. Clean this up.
+ */
+ fixup_rt_mutex_waiters(lock);
+
+ return ret;
+}
+
+/*
+ * Slow path try-lock function:
+ */
+static int __sched rt_mutex_slowtrylock(struct rt_mutex_base *lock)
+{
+ unsigned long flags;
+ int ret;
+
+ /*
+ * If the lock already has an owner we fail to get the lock.
+ * This can be done without taking the @lock->wait_lock as
+ * it is only being read, and this is a trylock anyway.
+ */
+ if (rt_mutex_owner(lock))
+ return 0;
+
+ /*
+ * The mutex has currently no owner. Lock the wait lock and try to
+ * acquire the lock. We use irqsave here to support early boot calls.
+ */
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
+
+ ret = __rt_mutex_slowtrylock(lock);
+
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+
+ return ret;
+}
+
+static __always_inline int __rt_mutex_trylock(struct rt_mutex_base *lock)
+{
+ if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
+ return 1;
+
+ return rt_mutex_slowtrylock(lock);
+}
+
+/*
+ * Slow path to release a rt-mutex.
+ */
+static void __sched rt_mutex_slowunlock(struct rt_mutex_base *lock)
+{
+ DEFINE_RT_WAKE_Q(wqh);
+ unsigned long flags;
+
+ /* irqsave required to support early boot calls */
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
+
+ debug_rt_mutex_unlock(lock);
+
+ /*
+ * We must be careful here if the fast path is enabled. If we
+ * have no waiters queued we cannot set owner to NULL here
+ * because of:
+ *
+ * foo->lock->owner = NULL;
+ * rtmutex_lock(foo->lock); <- fast path
+ * free = atomic_dec_and_test(foo->refcnt);
+ * rtmutex_unlock(foo->lock); <- fast path
+ * if (free)
+ * kfree(foo);
+ * raw_spin_unlock(foo->lock->wait_lock);
+ *
+ * So for the fastpath enabled kernel:
+ *
+ * Nothing can set the waiters bit as long as we hold
+ * lock->wait_lock. So we do the following sequence:
+ *
+ * owner = rt_mutex_owner(lock);
+ * clear_rt_mutex_waiters(lock);
+ * raw_spin_unlock(&lock->wait_lock);
+ * if (cmpxchg(&lock->owner, owner, 0) == owner)
+ * return;
+ * goto retry;
+ *
+ * The fastpath disabled variant is simple as all access to
+ * lock->owner is serialized by lock->wait_lock:
+ *
+ * lock->owner = NULL;
+ * raw_spin_unlock(&lock->wait_lock);
+ */
+ while (!rt_mutex_has_waiters(lock)) {
+ /* Drops lock->wait_lock ! */
+ if (unlock_rt_mutex_safe(lock, flags) == true)
+ return;
+ /* Relock the rtmutex and try again */
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
+ }
+
+ /*
+ * The wakeup next waiter path does not suffer from the above
+ * race. See the comments there.
+ *
+ * Queue the next waiter for wakeup once we release the wait_lock.
+ */
+ mark_wakeup_next_waiter(&wqh, lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+
+ rt_mutex_wake_up_q(&wqh);
+}
+
+static __always_inline void __rt_mutex_unlock(struct rt_mutex_base *lock)
+{
+ if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
+ return;
+
+ rt_mutex_slowunlock(lock);
+}
+
+#ifdef CONFIG_SMP
+static bool rtmutex_spin_on_owner(struct rt_mutex_base *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *owner)
+{
+ bool res = true;
+
+ rcu_read_lock();
+ for (;;) {
+ /* If owner changed, trylock again. */
+ if (owner != rt_mutex_owner(lock))
+ break;
+ /*
+ * Ensure that @owner is dereferenced after checking that
+ * the lock owner still matches @owner. If that fails,
+ * @owner might point to freed memory. If it still matches,
+ * the rcu_read_lock() ensures the memory stays valid.
+ */
+ barrier();
+ /*
+ * Stop spinning when:
+ * - the lock owner has been scheduled out
+ * - current is not longer the top waiter
+ * - current is requested to reschedule (redundant
+ * for CONFIG_PREEMPT_RCU=y)
+ * - the VCPU on which owner runs is preempted
+ */
+ if (!owner->on_cpu || need_resched() ||
+ rt_mutex_waiter_is_top_waiter(lock, waiter) ||
+ vcpu_is_preempted(task_cpu(owner))) {
+ res = false;
+ break;
+ }
+ cpu_relax();
+ }
+ rcu_read_unlock();
+ return res;
+}
+#else
+static bool rtmutex_spin_on_owner(struct rt_mutex_base *lock,
+ struct rt_mutex_waiter *waiter,
+ struct task_struct *owner)
+{
+ return false;
+}
+#endif
+
+#ifdef RT_MUTEX_BUILD_MUTEX
+/*
+ * Functions required for:
+ * - rtmutex, futex on all kernels
+ * - mutex and rwsem substitutions on RT kernels
+ */
+
/*
* Remove a waiter from a lock and give up
*
- * Must be called with lock->wait_lock held and interrupts disabled. I must
+ * Must be called with lock->wait_lock held and interrupts disabled. It must
* have just failed to try_to_take_rt_mutex().
*/
-static void __sched remove_waiter(struct rt_mutex *lock,
+static void __sched remove_waiter(struct rt_mutex_base *lock,
struct rt_mutex_waiter *waiter)
{
bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
struct task_struct *owner = rt_mutex_owner(lock);
- struct rt_mutex *next_lock;
+ struct rt_mutex_base *next_lock;
lockdep_assert_held(&lock->wait_lock);
raw_spin_lock_irq(&lock->wait_lock);
}
-/*
- * Recheck the pi chain, in case we got a priority setting
+/**
+ * rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
+ * @lock: the rt_mutex to take
+ * @ww_ctx: WW mutex context pointer
+ * @state: the state the task should block in (TASK_INTERRUPTIBLE
+ * or TASK_UNINTERRUPTIBLE)
+ * @timeout: the pre-initialized and started timer, or NULL for none
+ * @waiter: the pre-initialized rt_mutex_waiter
*
- * Called from sched_setscheduler
+ * Must be called with lock->wait_lock held and interrupts disabled
*/
-void __sched rt_mutex_adjust_pi(struct task_struct *task)
-{
- struct rt_mutex_waiter *waiter;
- struct rt_mutex *next_lock;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&task->pi_lock, flags);
-
- waiter = task->pi_blocked_on;
- if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
- raw_spin_unlock_irqrestore(&task->pi_lock, flags);
- return;
- }
- next_lock = waiter->lock;
- raw_spin_unlock_irqrestore(&task->pi_lock, flags);
-
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(task);
-
- rt_mutex_adjust_prio_chain(task, RT_MUTEX_MIN_CHAINWALK, NULL,
- next_lock, NULL, task);
-}
-
-void __sched rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
-{
- debug_rt_mutex_init_waiter(waiter);
- RB_CLEAR_NODE(&waiter->pi_tree_entry);
- RB_CLEAR_NODE(&waiter->tree_entry);
- waiter->task = NULL;
-}
-
-/**
- * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
- * @lock: the rt_mutex to take
- * @state: the state the task should block in (TASK_INTERRUPTIBLE
- * or TASK_UNINTERRUPTIBLE)
- * @timeout: the pre-initialized and started timer, or NULL for none
- * @waiter: the pre-initialized rt_mutex_waiter
- *
- * Must be called with lock->wait_lock held and interrupts disabled
- */
-static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state,
- struct hrtimer_sleeper *timeout,
- struct rt_mutex_waiter *waiter)
+static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
+ struct ww_acquire_ctx *ww_ctx,
+ unsigned int state,
+ struct hrtimer_sleeper *timeout,
+ struct rt_mutex_waiter *waiter)
{
+ struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
+ struct task_struct *owner;
int ret = 0;
for (;;) {
break;
}
+ if (build_ww_mutex() && ww_ctx) {
+ ret = __ww_mutex_check_kill(rtm, waiter, ww_ctx);
+ if (ret)
+ break;
+ }
+
+ if (waiter == rt_mutex_top_waiter(lock))
+ owner = rt_mutex_owner(lock);
+ else
+ owner = NULL;
raw_spin_unlock_irq(&lock->wait_lock);
- schedule();
+ if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner))
+ schedule();
raw_spin_lock_irq(&lock->wait_lock);
set_current_state(state);
if (res != -EDEADLOCK || detect_deadlock)
return;
+ if (build_ww_mutex() && w->ww_ctx)
+ return;
+
/*
* Yell loudly and stop the task right here.
*/
}
}
-/*
- * Slow path lock function:
+/**
+ * __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
+ * @lock: The rtmutex to block lock
+ * @ww_ctx: WW mutex context pointer
+ * @state: The task state for sleeping
+ * @chwalk: Indicator whether full or partial chainwalk is requested
+ * @waiter: Initializer waiter for blocking
*/
-static int __sched rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk)
+static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
+ struct ww_acquire_ctx *ww_ctx,
+ unsigned int state,
+ enum rtmutex_chainwalk chwalk,
+ struct rt_mutex_waiter *waiter)
{
- struct rt_mutex_waiter waiter;
- unsigned long flags;
- int ret = 0;
-
- rt_mutex_init_waiter(&waiter);
+ struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
+ struct ww_mutex *ww = ww_container_of(rtm);
+ int ret;
- /*
- * Technically we could use raw_spin_[un]lock_irq() here, but this can
- * be called in early boot if the cmpxchg() fast path is disabled
- * (debug, no architecture support). In this case we will acquire the
- * rtmutex with lock->wait_lock held. But we cannot unconditionally
- * enable interrupts in that early boot case. So we need to use the
- * irqsave/restore variants.
- */
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
+ lockdep_assert_held(&lock->wait_lock);
/* Try to acquire the lock again: */
if (try_to_take_rt_mutex(lock, current, NULL)) {
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+ if (build_ww_mutex() && ww_ctx) {
+ __ww_mutex_check_waiters(rtm, ww_ctx);
+ ww_mutex_lock_acquired(ww, ww_ctx);
+ }
return 0;
}
set_current_state(state);
- /* Setup the timer, when timeout != NULL */
- if (unlikely(timeout))
- hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS);
-
- ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
-
+ ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk);
if (likely(!ret))
- /* sleep on the mutex */
- ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
-
- if (unlikely(ret)) {
+ ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter);
+
+ if (likely(!ret)) {
+ /* acquired the lock */
+ if (build_ww_mutex() && ww_ctx) {
+ if (!ww_ctx->is_wait_die)
+ __ww_mutex_check_waiters(rtm, ww_ctx);
+ ww_mutex_lock_acquired(ww, ww_ctx);
+ }
+ } else {
__set_current_state(TASK_RUNNING);
- remove_waiter(lock, &waiter);
- rt_mutex_handle_deadlock(ret, chwalk, &waiter);
+ remove_waiter(lock, waiter);
+ rt_mutex_handle_deadlock(ret, chwalk, waiter);
}
/*
* unconditionally. We might have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
-
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
-
- /* Remove pending timer: */
- if (unlikely(timeout))
- hrtimer_cancel(&timeout->timer);
-
- debug_rt_mutex_free_waiter(&waiter);
-
return ret;
}
-static int __sched __rt_mutex_slowtrylock(struct rt_mutex *lock)
+static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
+ struct ww_acquire_ctx *ww_ctx,
+ unsigned int state)
{
- int ret = try_to_take_rt_mutex(lock, current, NULL);
+ struct rt_mutex_waiter waiter;
+ int ret;
- /*
- * try_to_take_rt_mutex() sets the lock waiters bit
- * unconditionally. Clean this up.
- */
- fixup_rt_mutex_waiters(lock);
+ rt_mutex_init_waiter(&waiter);
+ waiter.ww_ctx = ww_ctx;
+
+ ret = __rt_mutex_slowlock(lock, ww_ctx, state, RT_MUTEX_MIN_CHAINWALK,
+ &waiter);
+ debug_rt_mutex_free_waiter(&waiter);
return ret;
}
/*
- * Slow path try-lock function:
+ * rt_mutex_slowlock - Locking slowpath invoked when fast path fails
+ * @lock: The rtmutex to block lock
+ * @ww_ctx: WW mutex context pointer
+ * @state: The task state for sleeping
*/
-static int __sched rt_mutex_slowtrylock(struct rt_mutex *lock)
+static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
+ struct ww_acquire_ctx *ww_ctx,
+ unsigned int state)
{
unsigned long flags;
int ret;
/*
- * If the lock already has an owner we fail to get the lock.
- * This can be done without taking the @lock->wait_lock as
- * it is only being read, and this is a trylock anyway.
- */
- if (rt_mutex_owner(lock))
- return 0;
-
- /*
- * The mutex has currently no owner. Lock the wait lock and try to
- * acquire the lock. We use irqsave here to support early boot calls.
+ * Technically we could use raw_spin_[un]lock_irq() here, but this can
+ * be called in early boot if the cmpxchg() fast path is disabled
+ * (debug, no architecture support). In this case we will acquire the
+ * rtmutex with lock->wait_lock held. But we cannot unconditionally
+ * enable interrupts in that early boot case. So we need to use the
+ * irqsave/restore variants.
*/
raw_spin_lock_irqsave(&lock->wait_lock, flags);
-
- ret = __rt_mutex_slowtrylock(lock);
-
+ ret = __rt_mutex_slowlock_locked(lock, ww_ctx, state);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
return ret;
}
-/*
- * Performs the wakeup of the top-waiter and re-enables preemption.
- */
-void __sched rt_mutex_postunlock(struct wake_q_head *wake_q)
-{
- wake_up_q(wake_q);
-
- /* Pairs with preempt_disable() in mark_wakeup_next_waiter() */
- preempt_enable();
-}
-
-/*
- * Slow path to release a rt-mutex.
- *
- * Return whether the current task needs to call rt_mutex_postunlock().
- */
-static void __sched rt_mutex_slowunlock(struct rt_mutex *lock)
-{
- DEFINE_WAKE_Q(wake_q);
- unsigned long flags;
-
- /* irqsave required to support early boot calls */
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
-
- debug_rt_mutex_unlock(lock);
-
- /*
- * We must be careful here if the fast path is enabled. If we
- * have no waiters queued we cannot set owner to NULL here
- * because of:
- *
- * foo->lock->owner = NULL;
- * rtmutex_lock(foo->lock); <- fast path
- * free = atomic_dec_and_test(foo->refcnt);
- * rtmutex_unlock(foo->lock); <- fast path
- * if (free)
- * kfree(foo);
- * raw_spin_unlock(foo->lock->wait_lock);
- *
- * So for the fastpath enabled kernel:
- *
- * Nothing can set the waiters bit as long as we hold
- * lock->wait_lock. So we do the following sequence:
- *
- * owner = rt_mutex_owner(lock);
- * clear_rt_mutex_waiters(lock);
- * raw_spin_unlock(&lock->wait_lock);
- * if (cmpxchg(&lock->owner, owner, 0) == owner)
- * return;
- * goto retry;
- *
- * The fastpath disabled variant is simple as all access to
- * lock->owner is serialized by lock->wait_lock:
- *
- * lock->owner = NULL;
- * raw_spin_unlock(&lock->wait_lock);
- */
- while (!rt_mutex_has_waiters(lock)) {
- /* Drops lock->wait_lock ! */
- if (unlock_rt_mutex_safe(lock, flags) == true)
- return;
- /* Relock the rtmutex and try again */
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
- }
-
- /*
- * The wakeup next waiter path does not suffer from the above
- * race. See the comments there.
- *
- * Queue the next waiter for wakeup once we release the wait_lock.
- */
- mark_wakeup_next_waiter(&wake_q, lock);
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
-
- rt_mutex_postunlock(&wake_q);
-}
-
-/*
- * debug aware fast / slowpath lock,trylock,unlock
- *
- * The atomic acquire/release ops are compiled away, when either the
- * architecture does not support cmpxchg or when debugging is enabled.
- */
-static __always_inline int __rt_mutex_lock(struct rt_mutex *lock, long state,
- unsigned int subclass)
+static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
+ unsigned int state)
{
- int ret;
-
- might_sleep();
- mutex_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
-
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
- ret = rt_mutex_slowlock(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
- if (ret)
- mutex_release(&lock->dep_map, _RET_IP_);
- return ret;
+ return rt_mutex_slowlock(lock, NULL, state);
}
+#endif /* RT_MUTEX_BUILD_MUTEX */
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-/**
- * rt_mutex_lock_nested - lock a rt_mutex
- *
- * @lock: the rt_mutex to be locked
- * @subclass: the lockdep subclass
- */
-void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
-{
- __rt_mutex_lock(lock, TASK_UNINTERRUPTIBLE, subclass);
-}
-EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
-
-#else /* !CONFIG_DEBUG_LOCK_ALLOC */
-
-/**
- * rt_mutex_lock - lock a rt_mutex
- *
- * @lock: the rt_mutex to be locked
- */
-void __sched rt_mutex_lock(struct rt_mutex *lock)
-{
- __rt_mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0);
-}
-EXPORT_SYMBOL_GPL(rt_mutex_lock);
-#endif
-
-/**
- * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
- *
- * @lock: the rt_mutex to be locked
- *
- * Returns:
- * 0 on success
- * -EINTR when interrupted by a signal
- */
-int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
-{
- return __rt_mutex_lock(lock, TASK_INTERRUPTIBLE, 0);
-}
-EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
-
-/**
- * rt_mutex_trylock - try to lock a rt_mutex
- *
- * @lock: the rt_mutex to be locked
- *
- * This function can only be called in thread context. It's safe to call it
- * from atomic regions, but not from hard or soft interrupt context.
- *
- * Returns:
- * 1 on success
- * 0 on contention
- */
-int __sched rt_mutex_trylock(struct rt_mutex *lock)
-{
- int ret;
-
- if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
- return 0;
-
- /*
- * No lockdep annotation required because lockdep disables the fast
- * path.
- */
- if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
- return 1;
-
- ret = rt_mutex_slowtrylock(lock);
- if (ret)
- mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(rt_mutex_trylock);
-
-/**
- * rt_mutex_unlock - unlock a rt_mutex
- *
- * @lock: the rt_mutex to be unlocked
- */
-void __sched rt_mutex_unlock(struct rt_mutex *lock)
-{
- mutex_release(&lock->dep_map, _RET_IP_);
- if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
- return;
-
- rt_mutex_slowunlock(lock);
-}
-EXPORT_SYMBOL_GPL(rt_mutex_unlock);
-
+#ifdef RT_MUTEX_BUILD_SPINLOCKS
/*
- * Futex variants, must not use fastpath.
+ * Functions required for spin/rw_lock substitution on RT kernels
*/
-int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
-{
- return rt_mutex_slowtrylock(lock);
-}
-
-int __sched __rt_mutex_futex_trylock(struct rt_mutex *lock)
-{
- return __rt_mutex_slowtrylock(lock);
-}
/**
- * __rt_mutex_futex_unlock - Futex variant, that since futex variants
- * do not use the fast-path, can be simple and will not need to retry.
- *
- * @lock: The rt_mutex to be unlocked
- * @wake_q: The wake queue head from which to get the next lock waiter
+ * rtlock_slowlock_locked - Slow path lock acquisition for RT locks
+ * @lock: The underlying RT mutex
*/
-bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
- struct wake_q_head *wake_q)
+static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
{
- lockdep_assert_held(&lock->wait_lock);
-
- debug_rt_mutex_unlock(lock);
-
- if (!rt_mutex_has_waiters(lock)) {
- lock->owner = NULL;
- return false; /* done */
- }
-
- /*
- * We've already deboosted, mark_wakeup_next_waiter() will
- * retain preempt_disabled when we drop the wait_lock, to
- * avoid inversion prior to the wakeup. preempt_disable()
- * therein pairs with rt_mutex_postunlock().
- */
- mark_wakeup_next_waiter(wake_q, lock);
-
- return true; /* call postunlock() */
-}
-
-void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
-{
- DEFINE_WAKE_Q(wake_q);
- unsigned long flags;
- bool postunlock;
-
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
- postunlock = __rt_mutex_futex_unlock(lock, &wake_q);
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
-
- if (postunlock)
- rt_mutex_postunlock(&wake_q);
-}
+ struct rt_mutex_waiter waiter;
+ struct task_struct *owner;
-/**
- * __rt_mutex_init - initialize the rt_mutex
- *
- * @lock: The rt_mutex to be initialized
- * @name: The lock name used for debugging
- * @key: The lock class key used for debugging
- *
- * Initialize the rt_mutex to unlocked state.
- *
- * Initializing of a locked rt_mutex is not allowed
- */
-void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name,
- struct lock_class_key *key)
-{
- debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key, 0);
+ lockdep_assert_held(&lock->wait_lock);
- __rt_mutex_basic_init(lock);
-}
-EXPORT_SYMBOL_GPL(__rt_mutex_init);
+ if (try_to_take_rt_mutex(lock, current, NULL))
+ return;
-/**
- * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
- * proxy owner
- *
- * @lock: the rt_mutex to be locked
- * @proxy_owner:the task to set as owner
- *
- * No locking. Caller has to do serializing itself
- *
- * Special API call for PI-futex support. This initializes the rtmutex and
- * assigns it to @proxy_owner. Concurrent operations on the rtmutex are not
- * possible at this point because the pi_state which contains the rtmutex
- * is not yet visible to other tasks.
- */
-void __sched rt_mutex_init_proxy_locked(struct rt_mutex *lock,
- struct task_struct *proxy_owner)
-{
- __rt_mutex_basic_init(lock);
- rt_mutex_set_owner(lock, proxy_owner);
-}
+ rt_mutex_init_rtlock_waiter(&waiter);
-/**
- * rt_mutex_proxy_unlock - release a lock on behalf of owner
- *
- * @lock: the rt_mutex to be locked
- *
- * No locking. Caller has to do serializing itself
- *
- * Special API call for PI-futex support. This merrily cleans up the rtmutex
- * (debugging) state. Concurrent operations on this rt_mutex are not
- * possible because it belongs to the pi_state which is about to be freed
- * and it is not longer visible to other tasks.
- */
-void __sched rt_mutex_proxy_unlock(struct rt_mutex *lock)
-{
- debug_rt_mutex_proxy_unlock(lock);
- rt_mutex_set_owner(lock, NULL);
-}
+ /* Save current state and set state to TASK_RTLOCK_WAIT */
+ current_save_and_set_rtlock_wait_state();
-/**
- * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
- * @lock: the rt_mutex to take
- * @waiter: the pre-initialized rt_mutex_waiter
- * @task: the task to prepare
- *
- * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
- * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
- *
- * NOTE: does _NOT_ remove the @waiter on failure; must either call
- * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this.
- *
- * Returns:
- * 0 - task blocked on lock
- * 1 - acquired the lock for task, caller should wake it up
- * <0 - error
- *
- * Special API call for PI-futex support.
- */
-int __sched __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter,
- struct task_struct *task)
-{
- int ret;
+ task_blocks_on_rt_mutex(lock, &waiter, current, NULL, RT_MUTEX_MIN_CHAINWALK);
- lockdep_assert_held(&lock->wait_lock);
+ for (;;) {
+ /* Try to acquire the lock again */
+ if (try_to_take_rt_mutex(lock, current, &waiter))
+ break;
- if (try_to_take_rt_mutex(lock, task, NULL))
- return 1;
+ if (&waiter == rt_mutex_top_waiter(lock))
+ owner = rt_mutex_owner(lock);
+ else
+ owner = NULL;
+ raw_spin_unlock_irq(&lock->wait_lock);
- /* We enforce deadlock detection for futexes */
- ret = task_blocks_on_rt_mutex(lock, waiter, task,
- RT_MUTEX_FULL_CHAINWALK);
+ if (!owner || !rtmutex_spin_on_owner(lock, &waiter, owner))
+ schedule_rtlock();
- if (ret && !rt_mutex_owner(lock)) {
- /*
- * Reset the return value. We might have
- * returned with -EDEADLK and the owner
- * released the lock while we were walking the
- * pi chain. Let the waiter sort it out.
- */
- ret = 0;
+ raw_spin_lock_irq(&lock->wait_lock);
+ set_current_state(TASK_RTLOCK_WAIT);
}
- return ret;
-}
-
-/**
- * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
- * @lock: the rt_mutex to take
- * @waiter: the pre-initialized rt_mutex_waiter
- * @task: the task to prepare
- *
- * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
- * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
- *
- * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter
- * on failure.
- *
- * Returns:
- * 0 - task blocked on lock
- * 1 - acquired the lock for task, caller should wake it up
- * <0 - error
- *
- * Special API call for PI-futex support.
- */
-int __sched rt_mutex_start_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter,
- struct task_struct *task)
-{
- int ret;
-
- raw_spin_lock_irq(&lock->wait_lock);
- ret = __rt_mutex_start_proxy_lock(lock, waiter, task);
- if (unlikely(ret))
- remove_waiter(lock, waiter);
- raw_spin_unlock_irq(&lock->wait_lock);
-
- return ret;
-}
-
-/**
- * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
- * @lock: the rt_mutex we were woken on
- * @to: the timeout, null if none. hrtimer should already have
- * been started.
- * @waiter: the pre-initialized rt_mutex_waiter
- *
- * Wait for the lock acquisition started on our behalf by
- * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
- * rt_mutex_cleanup_proxy_lock().
- *
- * Returns:
- * 0 - success
- * <0 - error, one of -EINTR, -ETIMEDOUT
- *
- * Special API call for PI-futex support
- */
-int __sched rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
- struct hrtimer_sleeper *to,
- struct rt_mutex_waiter *waiter)
-{
- int ret;
+ /* Restore the task state */
+ current_restore_rtlock_saved_state();
- raw_spin_lock_irq(&lock->wait_lock);
- /* sleep on the mutex */
- set_current_state(TASK_INTERRUPTIBLE);
- ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
/*
- * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
- * have to fix that up.
+ * try_to_take_rt_mutex() sets the waiter bit unconditionally.
+ * We might have to fix that up:
*/
fixup_rt_mutex_waiters(lock);
- raw_spin_unlock_irq(&lock->wait_lock);
-
- return ret;
+ debug_rt_mutex_free_waiter(&waiter);
}
-/**
- * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
- * @lock: the rt_mutex we were woken on
- * @waiter: the pre-initialized rt_mutex_waiter
- *
- * Attempt to clean up after a failed __rt_mutex_start_proxy_lock() or
- * rt_mutex_wait_proxy_lock().
- *
- * Unless we acquired the lock; we're still enqueued on the wait-list and can
- * in fact still be granted ownership until we're removed. Therefore we can
- * find we are in fact the owner and must disregard the
- * rt_mutex_wait_proxy_lock() failure.
- *
- * Returns:
- * true - did the cleanup, we done.
- * false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
- * caller should disregards its return value.
- *
- * Special API call for PI-futex support
- */
-bool __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter)
+static __always_inline void __sched rtlock_slowlock(struct rt_mutex_base *lock)
{
- bool cleanup = false;
-
- raw_spin_lock_irq(&lock->wait_lock);
- /*
- * Do an unconditional try-lock, this deals with the lock stealing
- * state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter()
- * sets a NULL owner.
- *
- * We're not interested in the return value, because the subsequent
- * test on rt_mutex_owner() will infer that. If the trylock succeeded,
- * we will own the lock and it will have removed the waiter. If we
- * failed the trylock, we're still not owner and we need to remove
- * ourselves.
- */
- try_to_take_rt_mutex(lock, current, waiter);
- /*
- * Unless we're the owner; we're still enqueued on the wait_list.
- * So check if we became owner, if not, take us off the wait_list.
- */
- if (rt_mutex_owner(lock) != current) {
- remove_waiter(lock, waiter);
- cleanup = true;
- }
- /*
- * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
- * have to fix that up.
- */
- fixup_rt_mutex_waiters(lock);
-
- raw_spin_unlock_irq(&lock->wait_lock);
+ unsigned long flags;
- return cleanup;
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
+ rtlock_slowlock_locked(lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
}
-#ifdef CONFIG_DEBUG_RT_MUTEXES
-void rt_mutex_debug_task_free(struct task_struct *task)
-{
- DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
- DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
-}
-#endif
+#endif /* RT_MUTEX_BUILD_SPINLOCKS */
projects / linux-2.6-microblaze.git / blobdiff