Messages in this thread | | | Date | Mon, 1 Jul 2013 23:51:15 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH 4/5] metag: kick: prevent nested kick handlers |
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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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