Right. So the kernel disables the low priority interrupts to prevent any other low priority interrupts using fromISR APIs from accessing the critical region while it’s being accessed by another ISR already and prevents any high priority interrupt from fiddling with the critical section by asserting out hence not suggested to not fromISR in high priority ISRs.
To clarify: a lower priority interrupt has acquired a lock, and a high priority interrupt occurs. The higher priority interrupt will rightaway be executed but what happens to the lock? technically if the lock remains intact then we shouldn’t worry about higher priority interrupt fiddling with a critical section but that’s what I’m trying to clarify.