Commit 942d182b authored by Andrew Jones's avatar Andrew Jones Committed by Radim Krčmář
Browse files

arm/arm64: smp: add deadlock detection



on_cpu() and friends are a bit risky when implemented without IPIs
(no preemption), because we can easily get deadlocks. Luckily, it's
also easy to detect those deadlocks, and assert, to at least make
them easier to debug.
Signed-off-by: Andrew Jones's avatarAndrew Jones <drjones@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent ce024192
......@@ -76,9 +76,24 @@ typedef void (*on_cpu_func)(void *);
struct on_cpu_info {
on_cpu_func func;
void *data;
cpumask_t waiters;
};
static struct on_cpu_info on_cpu_info[NR_CPUS];
static void cpu_wait(int cpu)
{
int me = smp_processor_id();
if (cpu == me)
return;
cpumask_set_cpu(me, &on_cpu_info[cpu].waiters);
assert_msg(!cpumask_test_cpu(cpu, &on_cpu_info[me].waiters), "CPU%d <=> CPU%d deadlock detected", me, cpu);
while (!cpu_idle(cpu))
wfe();
cpumask_clear_cpu(me, &on_cpu_info[cpu].waiters);
}
void do_idle(void)
{
int cpu = smp_processor_id();
......@@ -117,8 +132,7 @@ void on_cpu_async(int cpu, void (*func)(void *data), void *data)
spin_unlock(&lock);
for (;;) {
while (!cpu_idle(cpu))
wfe();
cpu_wait(cpu);
spin_lock(&lock);
if ((volatile void *)on_cpu_info[cpu].func == NULL)
break;
......@@ -134,9 +148,7 @@ void on_cpu_async(int cpu, void (*func)(void *data), void *data)
void on_cpu(int cpu, void (*func)(void *data), void *data)
{
on_cpu_async(cpu, func, data);
while (!cpu_idle(cpu))
wfe();
cpu_wait(cpu);
}
void on_cpus(void (*func)(void))
......@@ -150,6 +162,14 @@ void on_cpus(void (*func)(void))
}
func();
for_each_present_cpu(cpu) {
if (cpu == me)
continue;
cpumask_set_cpu(me, &on_cpu_info[cpu].waiters);
assert_msg(!cpumask_test_cpu(cpu, &on_cpu_info[me].waiters), "CPU%d <=> CPU%d deadlock detected", me, cpu);
}
while (cpumask_weight(&cpu_idle_mask) < nr_cpus - 1)
wfe();
for_each_present_cpu(cpu)
cpumask_clear_cpu(me, &on_cpu_info[cpu].waiters);
}
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