...
is a pointer to a variable that is used to hold an error code:
OS_ERR_NONE
if If the call is successful and the mutex has been created.
OS_ERR_CREATE_ISR
if If OS_CFG_CALLED_FROM_ISR_CHK_EN set to 1 in os_cfg.h: if attempting to create a mutex from an ISR.
OS_ERR_OBJ_PTR_NULL
if If OS_CFG_ARG_CHK_EN is set to 1 in os_cfg.h: if p_mutex is a NULL pointer.
OS_ERR_ILLEGAL_CREATE_RUN_TIME
if If OS_SAFETY_CRITICAL_IEC61508 is defined: you called this after calling OSSafetyCriticalStart() and thus you are no longer allowed to create additional kernel objects.
...