> I have a very basic doubt here ... what makes it impossible to sleep > in an ISR? I mean, I know that the kernel preemption is disabled and > the kernel will panic, but I could not understand why? Because the interrupt which you are serving in the ISR has been masked to avoid preemption( true for maskable inetrrupts ).Any locks you are holding in ISR are now with you solely. So, if you try to sleep you take the locks you untill you are rescheduled and complete. This may lead to a deadlock for the lock resource.
Ok, but how about an ISR, that does not take any locks? Why can't we sleep in SUCH an ISR? AFAIK, taking a lock disables kernel preemption, and hence it is not allowed to sleep. So I think my question would boil down to why is sleeping not allowed when the kernel preemption is disabled. LL - To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs
