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[S390] outstanding interrupts vs. smp_send_stop 

The panic function will first print the panic message to the console,
then stop additional cpus with smp_send_stop and finally call the
function on the panic notifier list.
In case of an I/O based console the panic message will cause I/O to
be started and a function on the panic notifier list will wait for the
completion of the I/O. That does not work if an I/O completion interrupt
has already been delivered to a cpu that is then stopped by smp_send_stop.
To break this cyclic dependency add code to smp_send_stop that gives
the additional cpu the opportunity to complete outstanding interrupts.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2011-12-27 11:27:22 +01:00
parent 3a3954ceae
commit 85ac7ca597
2 changed files with 43 additions and 8 deletions
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1
arch/s390/include/asm/sigp.h
View File

@ -56,6 +56,7 @@ enum {
ec_schedule = 0,
ec_call_function,
ec_call_function_single,
ec_stop_cpu,
};
/*

50
arch/s390/kernel/smp.c
View File

@ -154,22 +154,52 @@ void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
smp_switch_to_cpu(func, data, sp, stap(), __cpu_logical_map[0]);
}
static void smp_stop_cpu(void)
{
while (sigp(smp_processor_id(), sigp_stop) == sigp_busy)
cpu_relax();
}
void smp_send_stop(void)
{
int cpu, rc;
cpumask_t cpumask;
int cpu;
u64 end;
/* Disable all interrupts/machine checks */
__load_psw_mask(psw_kernel_bits | PSW_MASK_DAT);
trace_hardirqs_off();
/* stop all processors */
for_each_online_cpu(cpu) {
if (cpu == smp_processor_id())
continue;
do {
rc = sigp(cpu, sigp_stop);
} while (rc == sigp_busy);
cpumask_copy(&cpumask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &cpumask);
if (oops_in_progress) {
/*
* Give the other cpus the opportunity to complete
* outstanding interrupts before stopping them.
*/
end = get_clock() + (1000000UL << 12);
for_each_cpu(cpu, &cpumask) {
set_bit(ec_stop_cpu, (unsigned long *)
&lowcore_ptr[cpu]->ext_call_fast);
while (sigp(cpu, sigp_emergency_signal) == sigp_busy &&
get_clock() < end)
cpu_relax();
}
while (get_clock() < end) {
for_each_cpu(cpu, &cpumask)
if (cpu_stopped(cpu))
cpumask_clear_cpu(cpu, &cpumask);
if (cpumask_empty(&cpumask))
break;
cpu_relax();
}
}
/* stop all processors */
for_each_cpu(cpu, &cpumask) {
while (sigp(cpu, sigp_stop) == sigp_busy)
cpu_relax();
while (!cpu_stopped(cpu))
cpu_relax();
}
@ -194,6 +224,9 @@ static void do_ext_call_interrupt(unsigned int ext_int_code,
*/
bits = xchg(&S390_lowcore.ext_call_fast, 0);
if (test_bit(ec_stop_cpu, &bits))
smp_stop_cpu();
if (test_bit(ec_schedule, &bits))
scheduler_ipi();
@ -202,6 +235,7 @@ static void do_ext_call_interrupt(unsigned int ext_int_code,
if (test_bit(ec_call_function_single, &bits))
generic_smp_call_function_single_interrupt();
}
/*