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locking/rtmutex: Add mutex variant for RT 

Add the necessary defines, helpers and API functions for replacing struct mutex on
a PREEMPT_RT enabled kernel with an rtmutex based variant.

No functional change when CONFIG_PREEMPT_RT=n

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.081517417@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-08-15 23:29:01 +02:00 committed by Ingo Molnar
parent f8635d509d
commit bb630f9f7a
4 changed files with 187 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
include/linux/mutex.h
View File

@ -20,6 +20,18 @@
#include <linux/osq_lock.h>
#include <linux/debug_locks.h>
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
, .dep_map = { \
.name = #lockname, \
.wait_type_inner = LD_WAIT_SLEEP, \
}
#else
# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
#endif
#ifndef CONFIG_PREEMPT_RT
/*
* Simple, straightforward mutexes with strict semantics:
*
@ -93,16 +105,6 @@ do { \
__mutex_init((mutex), #mutex, &__key); \
} while (0)
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
, .dep_map = { \
.name = #lockname, \
.wait_type_inner = LD_WAIT_SLEEP, \
}
#else
# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
#endif
#define __MUTEX_INITIALIZER(lockname) \
{ .owner = ATOMIC_LONG_INIT(0) \
, .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
@ -124,6 +126,50 @@ extern void __mutex_init(struct mutex *lock, const char *name,
*/
extern bool mutex_is_locked(struct mutex *lock);
#else /* !CONFIG_PREEMPT_RT */
/*
* Preempt-RT variant based on rtmutexes.
*/
#include <linux/rtmutex.h>
struct mutex {
struct rt_mutex_base rtmutex;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
};
#define __MUTEX_INITIALIZER(mutexname) \
{ \
.rtmutex = __RT_MUTEX_BASE_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_base_is_locked(&(l)->rtmutex)
#define __mutex_init(mutex, name, key) \
do { \
rt_mutex_base_init(&(mutex)->rtmutex); \
__mutex_rt_init((mutex), name, key); \
} while (0)
#define mutex_init(mutex) \
do { \
static struct lock_class_key __key; \
\
__mutex_init((mutex), #mutex, &__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.

4
kernel/locking/mutex.c
View File

@ -30,6 +30,7 @@
#include <linux/debug_locks.h>
#include <linux/osq_lock.h>
#ifndef CONFIG_PREEMPT_RT
#include "mutex.h"
#ifdef CONFIG_DEBUG_MUTEXES
@ -1066,7 +1067,8 @@ ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
}
EXPORT_SYMBOL(ww_mutex_lock_interruptible);
#endif
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
#endif /* !CONFIG_PREEMPT_RT */
/**
* atomic_dec_and_mutex_lock - return holding mutex if we dec to 0

122
kernel/locking/rtmutex_api.c
View File

@ -454,3 +454,125 @@ void rt_mutex_debug_task_free(struct task_struct *task)
DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
}
#endif
#ifdef CONFIG_PREEMPT_RT
/* 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_wait(&mutex->dep_map, name, key, 0, LD_WAIT_SLEEP);
}
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 */

11
lib/Kconfig.debug
View File

@ -1235,7 +1235,7 @@ config PROVE_LOCKING
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_RWSEMS
select DEBUG_WW_MUTEX_SLOWPATH
@ -1299,7 +1299,7 @@ config LOCK_STAT
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_LOCK_ALLOC
default n
@ -1335,7 +1335,7 @@ config DEBUG_SPINLOCK
config DEBUG_MUTEXES
bool "Mutex debugging: basic checks"
depends on DEBUG_KERNEL
depends on DEBUG_KERNEL && !PREEMPT_RT
help
This feature allows mutex semantics violations to be detected and
reported.
@ -1345,7 +1345,8 @@ config DEBUG_WW_MUTEX_SLOWPATH
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select DEBUG_LOCK_ALLOC
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if PREEMPT_RT
help
This feature enables slowpath testing for w/w mutex users by
injecting additional -EDEADLK wound/backoff cases. Together with
@ -1368,7 +1369,7 @@ config DEBUG_LOCK_ALLOC
bool "Lock debugging: detect incorrect freeing of live locks"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select DEBUG_SPINLOCK
select DEBUG_MUTEXES
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select LOCKDEP
help