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SyncCtl(), SyncCtl_r()

Perform an operation on a synchronization object

Synopsis:

#include <sys/neutrino.h>

int SyncCtl( int cmd,
             sync_t * sync,
             void * data );

int SyncCtl_r( int cmd,
               sync_t * sync,
               void * data );

Arguments:

cmd

The operation type; one of:

• _NTO_SCTL_GETPRIOCEILING -- get the ceiling priority of the mutex pointed to by sync and put it in the variable pointed to by data.
• _NTO_SCTL_SETPRIOCEILING -- return the original ceiling priority. Set the ceiling priority of the mutex pointed to by sync to the value pointed to by data.
• _NTO_SCTL_SETEVENT -- attach an event, pointed to by data, to the mutex pointed to by sync.

  ---

  You should use SyncMutexEvent() to do this.

  ---

sync

A pointer to the synchronization object that you want to manipulate.

data

A pointer to data associated with the command, or a place where the function can store the requested information, depending on the operation.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The SyncCtl() and SyncCtl_r() kernel calls let you:

• set or get a ceiling priority for a mutex

  or

• attach an event to a mutex so you'll be notified when the mutex changes to the DEAD state.

These functions are similar, except for the way they indicate errors. See the Returns section for details.

Instead of using these kernel calls directly, consider calling pthread_mutex_getprioceiling() or pthread_mutex_setprioceiling().

Returns:

The only difference between these functions is the way they indicate errors:

SyncCtl()

If an error occurs, the function returns -1 and sets errno. Any other value returned indicates success.

SyncCtl_r()

Returns EOK on success. This function does NOT set errno. If an error occurs, the function returns any value listed in the Errors section.

Errors:

EAGAIN

All kernel synchronization event objects are in use.

EFAULT

A fault occurred when the kernel tried to access sync or data.

EINVAL

The synchronization object pointed to by sync doesn't exist, or the ceiling priority value pointed to by data is out of range.

ENOSYS

The SyncCtl() and SyncCtl_r() functions aren't currently supported.

Classification:

QNX Neutrino

See also:

pthread_mutex_getprioceiling(), pthread_mutex_setprioceiling(), SyncCondvarSignal(), SyncCondvarWait(), SyncDestroy(), SyncMutexEvent(), SyncMutexLock(), SyncMutexRevive(), SyncMutexUnlock(), SyncTypeCreate()