Mutex APIs

Data Structures
struct	k_mutex

Macros
#define	K_MUTEX_DEFINE(name)
	Statically define and initialize a mutex. More...

Functions
int	k_mutex_init (struct k_mutex *mutex)
	Initialize a mutex. More...
int	k_mutex_lock (struct k_mutex *mutex, k_timeout_t timeout)
	Lock a mutex. More...
int	k_mutex_unlock (struct k_mutex *mutex)
	Unlock a mutex. More...

Detailed Description

Macro Definition Documentation

K_MUTEX_DEFINE

#define K_MUTEX_DEFINE

(

name

)

#include <include/kernel.h>

Value:

        STRUCT_SECTION_ITERABLE(k_mutex, name) = \
                Z_MUTEX_INITIALIZER(name)

Statically define and initialize a mutex.

The mutex can be accessed outside the module where it is defined using:

extern struct k_mutex <name>; 

Parameters

name	Name of the mutex.

Function Documentation

k_mutex_init()

int k_mutex_init

(

struct k_mutex *

mutex

)

#include <include/kernel.h>

Initialize a mutex.

This routine initializes a mutex object, prior to its first use.

Upon completion, the mutex is available and does not have an owner.

Parameters

mutex

Address of the mutex.

Return values

0	Mutex object created

k_mutex_lock()

int k_mutex_lock	(	struct k_mutex *	mutex,
		k_timeout_t	timeout
	)

#include <include/kernel.h>

Lock a mutex.

This routine locks mutex. If the mutex is locked by another thread, the calling thread waits until the mutex becomes available or until a timeout occurs.

A thread is permitted to lock a mutex it has already locked. The operation completes immediately and the lock count is increased by 1.

Mutexes may not be locked in ISRs.

Parameters

mutex	Address of the mutex.
timeout	Waiting period to lock the mutex, or one of the special values K_NO_WAIT and K_FOREVER.

Return values

0	Mutex locked.
-EBUSY	Returned without waiting.
-EAGAIN	Waiting period timed out.

k_mutex_unlock()

int k_mutex_unlock

(

struct k_mutex *

mutex

)

#include <include/kernel.h>

Unlock a mutex.

This routine unlocks mutex. The mutex must already be locked by the calling thread.

The mutex cannot be claimed by another thread until it has been unlocked by the calling thread as many times as it was previously locked by that thread.

Mutexes may not be unlocked in ISRs, as mutexes must only be manipulated in thread context due to ownership and priority inheritance semantics.

Parameters

mutex

Address of the mutex.

Return values

0	Mutex unlocked.
-EPERM	The current thread does not own the mutex
-EINVAL	The mutex is not locked