locking/rtmutex: Split API from implementation (531ae4b0) · Commits · EulixOS / Software / Kernel

kernel/locking/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -24,7 +24,7 @@ obj-$(CONFIG_SMP) += spinlock.o
		obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o
		obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
		obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o
		obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
		obj-$(CONFIG_RT_MUTEXES) += rtmutex_api.o
		obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
		obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
		obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o

kernel/locking/rtmutex.c

+17 −462

Original line number	Diff line number	Diff line
		@@ -11,14 +11,12 @@
		*
		* 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 "rtmutex_common.h"

		@@ -371,11 +369,6 @@ rt_mutex_cond_detect_deadlock(struct rt_mutex_waiter *waiter,
		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)
		{
		return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
		@@ -1112,42 +1105,6 @@ static void __sched remove_waiter(struct rt_mutex *lock,
		raw_spin_lock_irq(&lock->wait_lock);
		}

		/*
		* Recheck the pi chain, in case we got a priority setting
		*
		* Called from sched_setscheduler
		*/
		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
		@@ -1274,6 +1231,15 @@ static int __sched rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state,
		return ret;
		}

		static __always_inline int __rt_mutex_lock(struct rt_mutex *lock,
		unsigned int state)
		{
		if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
		return 0;

		return rt_mutex_slowlock(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
		}

		static int __sched __rt_mutex_slowtrylock(struct rt_mutex *lock)
		{
		int ret = try_to_take_rt_mutex(lock, current, NULL);
		@@ -1316,21 +1282,16 @@ static int __sched rt_mutex_slowtrylock(struct rt_mutex *lock)
		return ret;
		}

		/*
		* Performs the wakeup of the top-waiter and re-enables preemption.
		*/
		void __sched rt_mutex_postunlock(struct wake_q_head *wake_q)
		static __always_inline int __rt_mutex_trylock(struct rt_mutex *lock)
		{
		wake_up_q(wake_q);
		if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
		return 1;

		/* Pairs with preempt_disable() in mark_wakeup_next_waiter() */
		preempt_enable();
		return rt_mutex_slowtrylock(lock);
		}

		/*
		* 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)
		{
		@@ -1393,416 +1354,10 @@ static void __sched rt_mutex_slowunlock(struct rt_mutex *lock)
		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 void __rt_mutex_unlock(struct rt_mutex *lock)
		{
		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;
		}

		#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);

		/*
		* Futex variants, must not use fastpath.
		*/
		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
		*/
		bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
		struct wake_q_head *wake_q)
		{
		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);
		}

		/**
		* __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_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);

		__rt_mutex_basic_init(lock);
		}
		EXPORT_SYMBOL_GPL(__rt_mutex_init);

		/**
		* 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_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);
		}

		/**
		* __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;

		lockdep_assert_held(&lock->wait_lock);

		if (try_to_take_rt_mutex(lock, task, NULL))
		return 1;

		/* We enforce deadlock detection for futexes */
		ret = task_blocks_on_rt_mutex(lock, waiter, task,
		RT_MUTEX_FULL_CHAINWALK);

		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;
		}

		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;

		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.
		*/
		fixup_rt_mutex_waiters(lock);
		raw_spin_unlock_irq(&lock->wait_lock);

		return ret;
		}

		/**
		* 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)
		{
		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);

		return cleanup;
		}

		#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

kernel/locking/rtmutex_api.c

0 → 100644

+453 −0

File added.

Preview size limit exceeded, changes collapsed.

kernel/locking/rtmutex_common.h

+43 −35

Original line number	Diff line number	Diff line
		@@ -37,6 +37,33 @@ struct rt_mutex_waiter {
		u64 deadline;
		};

		/*
		* PI-futex support (proxy locking functions, etc.):
		*/
		extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
		struct task_struct *proxy_owner);
		extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
		extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter,
		struct task_struct *task);
		extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter,
		struct task_struct *task);
		extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
		struct hrtimer_sleeper *to,
		struct rt_mutex_waiter *waiter);
		extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter);

		extern int rt_mutex_futex_trylock(struct rt_mutex *l);
		extern int __rt_mutex_futex_trylock(struct rt_mutex *l);

		extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
		extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
		struct wake_q_head *wake_q);

		extern void rt_mutex_postunlock(struct wake_q_head *wake_q);

		/*
		* Must be guarded because this header is included from rcu/tree_plugin.h
		* unconditionally.
		@@ -78,13 +105,6 @@ static inline struct task_struct rt_mutex_owner(struct rt_mutex lock)

		return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
		}
		#else /* CONFIG_RT_MUTEXES */
		/* Used in rcu/tree_plugin.h */
		static inline struct task_struct rt_mutex_owner(struct rt_mutex lock)
		{
		return NULL;
		}
		#endif /* !CONFIG_RT_MUTEXES */

		/*
		* Constants for rt mutex functions which have a selectable deadlock
		@@ -108,34 +128,6 @@ static inline void __rt_mutex_basic_init(struct rt_mutex *lock)
		lock->waiters = RB_ROOT_CACHED;
		}

		/*
		* PI-futex support (proxy locking functions, etc.):
		*/
		extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
		struct task_struct *proxy_owner);
		extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
		extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
		extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter,
		struct task_struct *task);
		extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter,
		struct task_struct *task);
		extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
		struct hrtimer_sleeper *to,
		struct rt_mutex_waiter *waiter);
		extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
		struct rt_mutex_waiter *waiter);

		extern int rt_mutex_futex_trylock(struct rt_mutex *l);
		extern int __rt_mutex_futex_trylock(struct rt_mutex *l);

		extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
		extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
		struct wake_q_head *wqh);

		extern void rt_mutex_postunlock(struct wake_q_head *wake_q);

		/* Debug functions */
		static inline void debug_rt_mutex_unlock(struct rt_mutex *lock)
		{
		@@ -161,4 +153,20 @@ static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
		memset(waiter, 0x22, sizeof(*waiter));
		}

		static inline void 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;
		}

		#else /* CONFIG_RT_MUTEXES */
		/* Used in rcu/tree_plugin.h */
		static inline struct task_struct rt_mutex_owner(struct rt_mutex lock)
		{
		return NULL;
		}
		#endif /* !CONFIG_RT_MUTEXES */

		#endif