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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.10.16 at 13:23, <tianyu.lan@xxxxxxxxx> 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
> 
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> ---
>  xen/drivers/char/console.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index b0f74ce..184b523 100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -347,7 +347,7 @@ static void switch_serial_input(void)
>  static void __serial_rx(char c, struct cpu_user_regs *regs)
>  {
>      if ( xen_rx )
> -        return handle_keypress(c, regs, !in_irq());
> +        return handle_keypress(c, regs, true);

Together with one of your earlier patches having got reverted, I
think we need to take a step back here instead of going back to
what was requested to be changed from v2 of the original patch.
In particular I assume that the problem you're trying to address is
not limited to dump_timerq() - at least dump_runq() should be as
problematic on many-CPU systems.

I think (and I vaguely recall possibly having said so during earlier
review) that dump functions the output of which depends on CPU
count should get modeled after dump_registers(), and it might be
worth abstracting this in keyhandler.c. In any case quite likely the
other patch of yours (which the one here basically modifies) may
then also want to be reverted.

Jan

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