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

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

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.


>
>
>>
>> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
>> ---
>>  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);
>>
>>      /* Deliver input to guest buffer, unless it is already full. */
>>      if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
>> --
>> 2.9.3
>>

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