Hi Timur,

On 08/22/2015 12:45 AM, Timur Tabi wrote:

On 08/10/2015 12:05 PM, Timur Tabi wrote:

quoted

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This code was inherited from arch/arm which initially was always
dumping
the stack but it later gained the system_state check. Unless it's
useful
to anyone for debugging purposes, I'm ok with removing it.

Do you have patch for this one? My colleagues said that they met the
same problem :)

Dropping the call to dump_stack() would probably be sufficient.

Actually, I think we need to keep it.  I just heard from another
developer who does actually use it for debugging.

Hmm, could you please give a example for how it used?

I think the real problem is that emergency_restart() should not be
causing these outputs.  Shouldn't machine_restart() change the
system_state to SYSTEM_RESTART before it calls smp_send_stop()?

The system_state is set to SYSTEM_RESTART in kernel_restart_prepare(),
and kernel_restart() will call kernel_restart_prepare() and
machine_restart(), so if we change the system_state to SYSTEM_RESTART
in machine_restart(), it seems duplicate.

Could we just wait longer than one second in the following function?

void smp_send_stop(void)
{
         unsigned long timeout;

         if (num_online_cpus() > 1) {
                 cpumask_t mask;

                 cpumask_copy(&mask, cpu_online_mask);
                 cpumask_clear_cpu(smp_processor_id(), &mask);

                 smp_cross_call(&mask, IPI_CPU_STOP);
         }

         /* Wait up to one second for other CPUs to stop */
         timeout = USEC_PER_SEC;
         while (num_online_cpus() > 1 && timeout--)
                 udelay(1);

If we have lots of CPUs, one second seems not enough as it
print lots dump message.

Thanks
Hanjun