Messages in this thread | | | Date | Mon, 14 May 2007 12:46:26 +0530 | From | "Learning Linux" <> | Subject | Re: Why can't we sleep in an ISR? |
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> > 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.
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