Re: [Xen-devel] [PATCH] Xen: Force non-irq keyhandler to be run in tasklet when receive a debugkey from serial port

["Lan, Tianyu" <tianyu.lan@xxxxxxxxx>]

On 10/24/2016 9:38 PM, Konrad Rzeszutek Wilk wrote:
> On Mon, Oct 24, 2016 at 09:29:53PM +0800, Lan, Tianyu wrote:
> > On 10/24/2016 8:19 AM, Konrad Rzeszutek Wilk wrote:
> > > On Sat, Oct 22, 2016 at 07:23:03PM +0800, Lan Tianyu wrote:
> > > > __serial_rx() runs in either irq handler or timer handler and non-irq
> > > > keyhandler should not run in these contexts. So always force non-irq
> > > > keyhandler to run in tasklet when receive a debugkey from serial port
> > > If the machine is hung with an IRQ handler being stuck, and
> > > one does 'Ctrl-Ax3` followed by 'C' .. which would not be invoked
> > > (as it is not an IRQ handler??
> > If serial port's interrupt still works in this case, the 'C'
> > keyhandler kexec_crash() will be invoked in a tasklet. This behavior was
> > changed by my patches if includes this patch.
> Right, but the tasklet won't get to run at that point - as for example
> the IRQ handler is stuck - so tasklets never get run? Or maybe
> they do on another CPU?

If serial interrupt handler works, the cpu receiving serial port
interrupt should work normally. Tasklet_schedule() in the
handle_keypress() queues keyhandler tasklet to that cpu and tasklet also
should get to run at that point.
.

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