On Mon, 1 Jul 2013, James Hogan wrote:
> The main kick trigger handler iterates a list of kick handlers and calls
> each one. This is done with the kick_handlers_lock spin lock held, but
> this causes a problem on SMP where IPIs are implemented with kicks. A
> reschedule IPI calls scheduler_ipi() which uses irq_enter() and
> irq_exit(). This results in the scheduler being invoked with
> kick_handlers_lock held which can result in a nested kick trigger
> attempting to acquire the lock, resulting in deadlock.
>
> irq_enter() and irq_exit() can nest, so call them from the main kick
> interrupt handler so that softirqs are only handled after
> kick_handlers_lock is released.
This changelog is confusing. What I decode from the patch is, that you
are adding a missing irq_enter/exit pair to the kick_handler, right ?
Thanks,
tglx
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