...
the scheduler is locked.
OS_ERR_LOCK_NESTING_OVF
if If the user called this function too many times.
OS_ERR_OS_NOT_RUNNING
if If the function is called before calling OSStart().
OS_ERR_SCHED_LOCK_ISR
if If OS_CFG_CALLED_FROM_ISR_CHK_EN set to 1 in os_cfg.h: if you attempted to call OSSchedLock() from an ISR.
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