On 5/14/07, Learning Linux <learninglinux4@xxxxxxxxx> wrote:
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.
Thus to avoid this, kernel developers disable preemption and also on every schedule check if you are *in_interrupt*, if you are, you are probably doing something really bad.So its better to panic in such case.
This is my naive understanding.
Please CMIIW.
Thanks
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.
Thus to avoid this, kernel developers disable preemption and also on every schedule check if you are *in_interrupt*, if you are, you are probably doing something really bad.So its better to panic in such case.
This is my naive understanding.
Please CMIIW.
Thanks
TIA,
LL
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