diff options
Diffstat (limited to 'include/linux/rwsem.h')
| -rw-r--r-- | include/linux/rwsem.h | 130 |
1 files changed, 113 insertions, 17 deletions
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 25e3fde85617..c8b543d428b0 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -11,11 +11,24 @@ #include <linux/linkage.h> #include <linux/types.h> -#include <linux/kernel.h> #include <linux/list.h> #include <linux/spinlock.h> #include <linux/atomic.h> #include <linux/err.h> +#include <linux/cleanup.h> + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# define __RWSEM_DEP_MAP_INIT(lockname) \ + .dep_map = { \ + .name = #lockname, \ + .wait_type_inner = LD_WAIT_SLEEP, \ + }, +#else +# define __RWSEM_DEP_MAP_INIT(lockname) +#endif + +#ifndef CONFIG_PREEMPT_RT + #ifdef CONFIG_RWSEM_SPIN_ON_OWNER #include <linux/osq_lock.h> #endif @@ -53,26 +66,26 @@ struct rw_semaphore { #endif }; -/* In all implementations count != 0 means locked */ +#define RWSEM_UNLOCKED_VALUE 0UL +#define RWSEM_WRITER_LOCKED (1UL << 0) +#define __RWSEM_COUNT_INIT(name) .count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE) + static inline int rwsem_is_locked(struct rw_semaphore *sem) { - return atomic_long_read(&sem->count) != 0; + return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE; } -#define RWSEM_UNLOCKED_VALUE 0L -#define __RWSEM_COUNT_INIT(name) .count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE) +static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem) +{ + WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE); +} -/* Common initializer macros and functions */ +static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem) +{ + WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED)); +} -#ifdef CONFIG_DEBUG_LOCK_ALLOC -# define __RWSEM_DEP_MAP_INIT(lockname) \ - .dep_map = { \ - .name = #lockname, \ - .wait_type_inner = LD_WAIT_SLEEP, \ - }, -#else -# define __RWSEM_DEP_MAP_INIT(lockname) -#endif +/* Common initializer macros and functions */ #ifdef CONFIG_DEBUG_RWSEMS # define __RWSEM_DEBUG_INIT(lockname) .magic = &lockname, @@ -110,7 +123,7 @@ do { \ /* * This is the same regardless of which rwsem implementation that is being used. - * It is just a heuristic meant to be called by somebody alreadying holding the + * It is just a heuristic meant to be called by somebody already holding the * rwsem to see if somebody from an incompatible type is wanting access to the * lock. */ @@ -119,10 +132,84 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem) return !list_empty(&sem->wait_list); } +#else /* !CONFIG_PREEMPT_RT */ + +#include <linux/rwbase_rt.h> + +struct rw_semaphore { + struct rwbase_rt rwbase; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif +}; + +#define __RWSEM_INITIALIZER(name) \ + { \ + .rwbase = __RWBASE_INITIALIZER(name), \ + __RWSEM_DEP_MAP_INIT(name) \ + } + +#define DECLARE_RWSEM(lockname) \ + struct rw_semaphore lockname = __RWSEM_INITIALIZER(lockname) + +extern void __init_rwsem(struct rw_semaphore *rwsem, const char *name, + struct lock_class_key *key); + +#define init_rwsem(sem) \ +do { \ + static struct lock_class_key __key; \ + \ + __init_rwsem((sem), #sem, &__key); \ +} while (0) + +static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem) +{ + return rw_base_is_locked(&sem->rwbase); +} + +static __always_inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem) +{ + WARN_ON(!rwsem_is_locked(sem)); +} + +static __always_inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem) +{ + WARN_ON(!rw_base_is_write_locked(&sem->rwbase)); +} + +static __always_inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return rw_base_is_contended(&sem->rwbase); +} + +#endif /* CONFIG_PREEMPT_RT */ + +/* + * The functions below are the same for all rwsem implementations including + * the RT specific variant. + */ + +static inline void rwsem_assert_held(const struct rw_semaphore *sem) +{ + if (IS_ENABLED(CONFIG_LOCKDEP)) + lockdep_assert_held(sem); + else + rwsem_assert_held_nolockdep(sem); +} + +static inline void rwsem_assert_held_write(const struct rw_semaphore *sem) +{ + if (IS_ENABLED(CONFIG_LOCKDEP)) + lockdep_assert_held_write(sem); + else + rwsem_assert_held_write_nolockdep(sem); +} + /* * lock for reading */ extern void down_read(struct rw_semaphore *sem); +extern int __must_check down_read_interruptible(struct rw_semaphore *sem); extern int __must_check down_read_killable(struct rw_semaphore *sem); /* @@ -151,6 +238,13 @@ extern void up_read(struct rw_semaphore *sem); */ extern void up_write(struct rw_semaphore *sem); +DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T)) +DEFINE_GUARD_COND(rwsem_read, _try, down_read_trylock(_T)) +DEFINE_GUARD_COND(rwsem_read, _intr, down_read_interruptible(_T) == 0) + +DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) +DEFINE_GUARD_COND(rwsem_write, _try, down_write_trylock(_T)) + /* * downgrade write lock to read lock */ @@ -171,6 +265,7 @@ extern void downgrade_write(struct rw_semaphore *sem); * See Documentation/locking/lockdep-design.rst for more details.) */ extern void down_read_nested(struct rw_semaphore *sem, int subclass); +extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass); extern void down_write_nested(struct rw_semaphore *sem, int subclass); extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass); extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock); @@ -179,7 +274,7 @@ extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map * do { \ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ _down_write_nest_lock(sem, &(nest_lock)->dep_map); \ -} while (0); +} while (0) /* * Take/release a lock when not the owner will release it. @@ -191,6 +286,7 @@ extern void down_read_non_owner(struct rw_semaphore *sem); extern void up_read_non_owner(struct rw_semaphore *sem); #else # define down_read_nested(sem, subclass) down_read(sem) +# define down_read_killable_nested(sem, subclass) down_read_killable(sem) # define down_write_nest_lock(sem, nest_lock) down_write(sem) # define down_write_nested(sem, subclass) down_write(sem) # define down_write_killable_nested(sem, subclass) down_write_killable(sem) |