unl_mtx

Outline

Unlock mutex.

C format

 ER      unl_mtx (ID mtxid);

Parameter(s)

I/O	Parameter	Description
I	ID mtxid;	ID number of the mutex to be unlocked.

Explanation

This service call unlocks the locked mutex specified by parameter mtxid.

If a task has been queued to the target mutex wait queue when this service call is issued, mutex lock processing is performed by the task (the first task in the wait queue) immediately after mutex unlock processing.

As a result, the task is unlinked from the wait queue and moves from the WAITING state (mutex wait state) to the READY state, or from the WAITING-SUSPENDED state to the SUSPENDED state.

Note A locked mutex can be unlocked only by the task that locked the mutex.
If this service call is issued for a mutex that was not locked by an invoking task, no processing is performed but E_ILUSE is returned.

Return value

Macro	Value	Description
E_OK	0	Normal completion.
E_ID	-18	Invalid ID number. - mtxid < 0x0 - mtxid > Maximum ID number
E_CTX	-25	Context error. - This service call was issued from a non-task. - This service call was issued in the CPU locked state.
E_ILUSE	-28	Illegal service call use. - Multiple unlocking of a mutex. - The invoking task does not have the specified mutex locked.
E_NOEXS	-42	Non-existent object. - Specified mutex is not registered.