mutex semantics are sufficient for your code, then there are a couple
of advantages of mutexes:
- - 'struct mutex' is smaller on most architectures: .e.g on x86,
+ - 'struct mutex' is smaller on most architectures: E.g. on x86,
'struct semaphore' is 20 bytes, 'struct mutex' is 16 bytes.
A smaller structure size means less RAM footprint, and better
CPU-cache utilization.
void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
int mutex_lock_interruptible_nested(struct mutex *lock,
unsigned int subclass);
+ int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
# include <linux/mutex-debug.h>
#else
# define __DEBUG_MUTEX_INITIALIZER(lockname)
+/**
+ * mutex_init - initialize the mutex
+ * @mutex: the mutex to be initialized
+ *
+ * Initialize the mutex to unlocked state.
+ *
+ * It is not allowed to initialize an already locked mutex.
+ */
# define mutex_init(mutex) \
do { \
static struct lock_class_key __key; \
# include <asm/mutex.h>
#endif
-/***
- * mutex_init - initialize the mutex
- * @lock: the mutex to be initialized
- * @key: the lock_class_key for the class; used by mutex lock debugging
- *
- * Initialize the mutex to unlocked state.
- *
- * It is not allowed to initialize an already locked mutex.
- */
void
__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
{
static __used noinline void __sched
__mutex_lock_slowpath(atomic_t *lock_count);
-/***
+/**
* mutex_lock - acquire the mutex
* @lock: the mutex to be acquired
*
static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
-/***
+/**
* mutex_unlock - release the mutex
* @lock: the mutex to be released
*
static noinline int __sched
__mutex_lock_interruptible_slowpath(atomic_t *lock_count);
-/***
- * mutex_lock_interruptible - acquire the mutex, interruptable
+/**
+ * mutex_lock_interruptible - acquire the mutex, interruptible
* @lock: the mutex to be acquired
*
* Lock the mutex like mutex_lock(), and return 0 if the mutex has
return prev == 1;
}
-/***
- * mutex_trylock - try acquire the mutex, without waiting
+/**
+ * mutex_trylock - try to acquire the mutex, without waiting
* @lock: the mutex to be acquired
*
* Try to acquire the mutex atomically. Returns 1 if the mutex
* has been acquired successfully, and 0 on contention.
*
* NOTE: this function follows the spin_trylock() convention, so
- * it is negated to the down_trylock() return values! Be careful
+ * it is negated from the down_trylock() return values! Be careful
* about this when converting semaphore users to mutexes.
*
* This function must not be used in interrupt context. The