Hi,
One question from Linux-Tag was about the lack of documentation about/in
the kernel. I try to maintain docbook entries when I modify code, even
though I think it's mostly wasted time: Virtually noone reads it anyway,
instead armchair logic on lkml.
Steven wrote:
Here we see that task 2 can spin with interrupts off, while the first task
is servicing an interrupt, and God forbid if the IRQ handler sends some
kind of SMP signal to the CPU running task 2 since that would be a
deadlock. Granted, this is a hypothetical situation, but makes using
spin_lock with interrupts enabled a little scary.
Not, it's not even a hypothetical situation. It's an explicitely
forbidden situation: SMP signals are sent with smp_call_function and the
documentation to that function clearly says:
*
* You must not call this function with disabled interrupts or from a
* hardware interrupt handler or from a bottom half handler.
*/
--
Manfred
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