Messages in this thread | | | Date | Tue, 24 Jun 2014 14:33:41 -0600 | From | Stephen Warren <> | Subject | Re: [PATCH 2/6] irq_work: Implement remote queueing |
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On 06/10/2014 09:15 AM, Frederic Weisbecker wrote: > irq work currently only supports local callbacks. However its code > is mostly ready to run remote callbacks and we have some potential user. > > The full nohz subsystem currently open codes its own remote irq work > on top of the scheduler ipi when it wants a CPU to reevaluate its next > tick. However this ad hoc solution bloats the scheduler IPI. > > Lets just extend the irq work subsystem to support remote queuing on top > of the generic SMP IPI to handle this kind of user. This shouldn't add > noticeable overhead.
I'm running next-20140624 on an ARM system, and this patch causes CPU hot(un)plug to Oops for me; the following fires:
void irq_work_run(void) { BUG_ON(!in_irq());
I found that Linus's master (8b8f5d971584 "Merge tag 'compress-3.16-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core") works fine. I found that this commit inside the tip(?) tree works fine (478850160636 "irq_work: Implement remote queueing"). However, if I merge the two together, I hit that BUG_ON.
I think the issue is:
This commit adds a call from generic_smp_call_function_single_interrupt() to irq_work_run().
Srivatsa's patch adds a call from hotplug_cfd() to flush_smp_call_function_queue() to, which I imagine happens in non-interrupt context. Note that this patch moves most of the body of generic_smp_call_function_single_interrupt() into flush_smp_call_function_queue().
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