Messages in this thread Patch in this message | | | Date | Tue, 13 Jul 2021 17:11:33 +0200 | From | Thomas Gleixner <> | Subject | [patch 39/50] locking/rtmutex: Add mutex variant for RT |
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From: Thomas Gleixner <tglx@linutronix.de>
Add the necessary defines, helpers and API functions for replacing mutex on a PREEMPT_RT enabled kernel with a rtmutex based variant.
If PREEMPT_RT is enabled then the regular 'struct mutex' is renamed to 'struct __mutex', which is still typedef'ed as '_mutex_t' to allow the standalone compilation and utilization of ww_mutex.
No functional change when CONFIG_PREEMPT_RT=n
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- include/linux/mutex.h | 53 ++++++++++++++++++- kernel/locking/rtmutex_api.c | 122 +++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 173 insertions(+), 2 deletions(-) --- diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 827c32bb44bc..2cfc234a786d 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -64,7 +64,12 @@ * built on the regular mutex code in RT kernels while mutex itself is * substituted by a rt_mutex. */ -typedef struct mutex { +#ifndef CONFIG_PREEMPT_RT +typedef struct mutex +#else +typedef struct __mutex +#endif +{ atomic_long_t owner; raw_spinlock_t wait_lock; #ifdef CONFIG_MUTEX_SPIN_ON_OWNER @@ -94,6 +99,7 @@ extern void _mutex_t_destroy(_mutex_t *lock); static inline void _mutex_t_destroy(_mutex_t *lock) {} #endif +#ifndef CONFIG_PREEMPT_RT /** * mutex_init - initialize the mutex * @mutex: the mutex to be initialized @@ -159,6 +165,51 @@ static __always_inline int mutex_trylock(struct mutex *lock) return _mutex_t_trylock(lock); } +#else /* !CONFIG_PREEMPT_RT */ +/* + * Preempt-RT variant based on rtmutexes. + */ +#include <linux/rtmutex.h> + +struct mutex { + struct rt_mutex rtmutex; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif +}; + +#define __MUTEX_INITIALIZER(mutexname) \ + { \ + .rtmutex = __RT_MUTEX_INITIALIZER(mutexname.rtmutex) \ + __DEP_MAP_MUTEX_INITIALIZER(mutexname) \ + } + +#define DEFINE_MUTEX(mutexname) \ + struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) + +extern void __mutex_rt_init(struct mutex *lock, const char *name, + struct lock_class_key *key); +extern int mutex_trylock(struct mutex *lock); + +static inline void mutex_destroy(struct mutex *lock) { } + +#define mutex_is_locked(l) rt_mutex_is_locked(&(l)->rtmutex) + +#define mutex_init(mutex) \ +do { \ + static struct lock_class_key __key; \ + \ + rt_mutex_init(&(mutex)->rtmutex); \ + __mutex_rt_init((mutex), #mutex, &__key); \ +} while (0) + +#define __mutex_init(mutex, name, key) \ +do { \ + rt_mutex_init(&(mutex)->rtmutex); \ + __mutex_rt_init((mutex), name, key); \ +} while (0) +#endif /* CONFIG_PREEMPT_RT */ + /* * See kernel/locking/mutex.c for detailed documentation of these APIs. * Also see Documentation/locking/mutex-design.rst. diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c index d9a2ec9c1ad4..1091a53eb99f 100644 --- a/kernel/locking/rtmutex_api.c +++ b/kernel/locking/rtmutex_api.c @@ -512,4 +512,124 @@ void rwsem_rt_mutex_unlock(struct rt_mutex *lock) rt_mutex_slowunlock(lock); } -#endif + +/* Mutexes */ +void __mutex_rt_init(struct mutex *mutex, const char *name, + struct lock_class_key *key) +{ + debug_check_no_locks_freed((void *)mutex, sizeof(*mutex)); + lockdep_init_map(&mutex->dep_map, name, key, 0); +} +EXPORT_SYMBOL(__mutex_rt_init); + +static __always_inline int __mutex_lock_common(struct mutex *lock, + unsigned int state, + unsigned int subclass, + struct lockdep_map *nest_lock, + unsigned long ip) +{ + int ret; + + might_sleep(); + mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip); + ret = __rt_mutex_lock(&lock->rtmutex, state); + if (ret) + mutex_release(&lock->dep_map, ip); + else + lock_acquired(&lock->dep_map, ip); + return ret; +} + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +void __sched mutex_lock_nested(struct mutex *lock, unsigned int subclass) +{ + __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_); +} +EXPORT_SYMBOL_GPL(mutex_lock_nested); + +void __sched _mutex_lock_nest_lock(struct mutex *lock, + struct lockdep_map *nest_lock) +{ + __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest_lock, _RET_IP_); +} +EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock); + +int __sched mutex_lock_interruptible_nested(struct mutex *lock, + unsigned int subclass) +{ + return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_); +} +EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); + +int __sched mutex_lock_killable_nested(struct mutex *lock, + unsigned int subclass) +{ + return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_); +} +EXPORT_SYMBOL_GPL(mutex_lock_killable_nested); + +void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass) +{ + int token; + + might_sleep(); + + token = io_schedule_prepare(); + __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_); + io_schedule_finish(token); +} +EXPORT_SYMBOL_GPL(mutex_lock_io_nested); + +#else /* CONFIG_DEBUG_LOCK_ALLOC */ + +void __sched mutex_lock(struct mutex *lock) +{ + __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_); +} +EXPORT_SYMBOL(mutex_lock); + +int __sched mutex_lock_interruptible(struct mutex *lock) +{ + return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_); +} +EXPORT_SYMBOL(mutex_lock_interruptible); + +int __sched mutex_lock_killable(struct mutex *lock) +{ + return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_); +} +EXPORT_SYMBOL(mutex_lock_killable); + +void __sched mutex_lock_io(struct mutex *lock) +{ + int token = io_schedule_prepare(); + + __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_); + io_schedule_finish(token); +} +EXPORT_SYMBOL(mutex_lock_io); +#endif /* !CONFIG_DEBUG_LOCK_ALLOC */ + +int __sched mutex_trylock(struct mutex *lock) +{ + int ret; + + if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task())) + return 0; + + ret = __rt_mutex_trylock(&lock->rtmutex); + if (ret) + mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); + + return ret; +} +EXPORT_SYMBOL(mutex_trylock); + +void __sched mutex_unlock(struct mutex *lock) +{ + mutex_release(&lock->dep_map, _RET_IP_); + __rt_mutex_unlock(&lock->rtmutex); +} +EXPORT_SYMBOL(mutex_unlock); + +#endif /* CONFIG_PREEMPT_RT */
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