Re: Sleeping in the interrupt handler

[Jan Hudec <bulb@ucw.cz>]

On Tue, Jul 01, 2003 at 06:22:29PM +0200, Martin Maletinsky wrote:
> I know, that you are not allowed to sleep in an interrupt handler. How
> ever I am interested to understand the reason(s) for that. Was this
> a design decision (e.g. to simplify things) for the Linux kernel, or
> is there a fundamental reason that makes sleeping interrupt handlers
> simply impossible? What about the page fault handler - it (probably)
> sleeps when it has to swap in a page, why is it possible to sleep for
> the page fault handler and not for an interrupt handler?

Sleeping is implemented using scheduler. Scheduler only schedules tasks
(design decision to keep it simple). So you need a task context to sleep
in. Interrupt is not tied to a process (and uses stack of whichever
happens to be scheduled) so it can't use the context because it does not
have to be in a sane state.

-------------------------------------------------------------------------------
						 Jan 'Bulb' Hudec <bulb@ucw.cz>
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