===================================================================
@@ -235,6 +235,7 @@ void acpi_processor_ppc_exit(void)
acpi_processor_ppc_status &= ~PPC_REGISTERED;
}
+static DEFINE_MUTEX(acpi_cpufreq_load_lock);
/*
* Do a quick check if the systems looks like it should use ACPI
* cpufreq. We look at a _PCT method being available, but don't
@@ -246,8 +247,12 @@ void acpi_processor_load_module(struct a
acpi_status status = 0;
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
- if (!arch_has_acpi_pdc() || requested)
+ mutex_lock(&acpi_cpufreq_load_lock);
+ if (!arch_has_acpi_pdc() || requested) {
+ mutex_unlock(&acpi_cpufreq_load_lock);
return;
+ }
+
status = acpi_evaluate_object(pr->handle, "_PCT", NULL, &buffer);
if (!ACPI_FAILURE(status)) {
printk(KERN_INFO PREFIX "Requesting acpi_cpufreq\n");
@@ -255,6 +260,7 @@ void acpi_processor_load_module(struct a
requested = 1;
}
kfree(buffer.pointer);
+ mutex_unlock(&acpi_cpufreq_load_lock);
}
static int acpi_processor_get_performance_control(struct acpi_processor *pr)
There is racing in __acpi_processor_start ==> acpi_processor_load_module ==> request_module_nowait/requested = 1 before first pr path to have requested set, second cpu would request again. that will cause acpi_cpufreq_early_init to be called in parallel, that will cause data curruption in acpi_cpufreq_early_init... and intermittent crash. So add mutex to protect it. Signed-off-by: Yinghai Lu <yinghai@kernel.org> --- drivers/acpi/processor_perflib.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html