Re: [PATCH 2/6] irq_work: Implement remote queueing

[Stephen Warren <swarren@wwwdotorg.org>]

On 06/25/2014 04:19 AM, Peter Zijlstra wrote:
> On Wed, Jun 25, 2014 at 03:24:11PM +0530, Srivatsa S. Bhat wrote:
>> Wait, that was a stupid idea. hotplug_cfd() already invokes irq_work_run
>> indirectly via flush_smp_call_function_queue(). So irq_work_cpu_notify()
>> doesn't need to invoke it again, AFAIU. So perhaps we can get rid of
>> irq_work_cpu_notify() altogether?
> 
> Just so...
> 
> getting up at 6am and sitting in an airport terminal doesn't seem to
> agree with me; any more silly fail here?
> 
> ---
> Subject: irq_work: Remove BUG_ON in irq_work_run()
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Wed Jun 25 07:13:07 CEST 2014
> 
> Because of a collision with 8d056c48e486 ("CPU hotplug, smp: flush any
> pending IPI callbacks before CPU offline"), which ends up calling
> hotplug_cfd()->flush_smp_call_function_queue()->irq_work_run(), which
> is not from IRQ context.
> 
> And since that already calls irq_work_run() from the hotplug path,
> remove our entire hotplug handling.

Tested-by: Stephen Warren <swarren@nvidia.com>

[with the s/static// already mentioned in this thread, obviously:-)]