Initialize a mutex
Synopsis:
#include <pthread.h>
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
int pthread_mutex_init(
pthread_mutex_t* mutex,
const pthread_mutexattr_t* attr );
Arguments:
- mutex
- A pointer to the pthread_mutex_t object that you want to initialize.
Note:
It's always safe, and typically faster, to assure that mutex is 32-bit aligned.
- attr
- NULL, or a pointer to a pthread_mutexattr_t
object that specifies the attributes that you want to use for the mutex.
For more information, see
pthread_mutexattr_init().
Library:
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
Description:
The pthread_mutex_init() function initializes the given mutex
object, using the attributes specified by the mutex attributes
object attr. If attr is NULL, then
the mutex is initialized with the default attributes (see
pthread_mutexattr_init()).
After initialization, the mutex is in an
unlocked state.
CAUTION:
You should allocate synchronization objects only in normal memory mappings.
On certain processors, atomic operations such as calls to
pthread_mutex_lock()
will cause a fault if the control structure is allocated in uncached memory.
You can initialize a statically allocated mutex with the default
attributes by assigning to it the macro
PTHREAD_MUTEX_INITIALIZER or
PTHREAD_RMUTEX_INITIALIZER (for recursive mutexes).
Note:
To destroy a mutex, call
pthread_mutex_destroy().
Once you've destroyed a mutex, don't reuse it without reinitializing it by
calling
pthread_mutex_init().
Returns:
- EOK
- Success.
- EFAULT
- A fault occurred when the kernel tried to access mutex or
attr.
- EINVAL
- The value specified by attr is invalid.
- ENOMEM
- All kernel synchronization objects are in use.
Classification:
POSIX 1003.1
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
No |
| Signal handler |
Yes |
| Thread |
Yes |