[PATCH 25/48] ACPI: Check the returned value of set_cpus_allowed_ptr before T-state operation

Len Brown
2011-01-12T18:00:18Z

From: Zhao Yakui <yakui.zhao@intel.com>

Now before it executes the T-state operation on one CPU, it will try to
migrate to the target CPU. Especially this is required on the system that
uses the MSR_IA32_THERMAL_CONTROL register to switch T-state.
But unfortunately it doesn't check whether the migration is successful or not.
In such case we will get/set the incorrect T-state on the offline CPU as
it fails in the migration to the offline CPU.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/acpi/processor_throttling.c | 24 +++++++++++++++++++++---
1 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index ff36327..ffc859c 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -876,7 +876,11 @@ static int acpi_processor_get_throttling(struct acpi_processor *pr)
*/
cpumask_copy(saved_mask, &current->cpus_allowed);
/* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(pr->id));
+ if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
+ /* Can't migrate to the target pr->id CPU. Exit */
+ free_cpumask_var(saved_mask);
+ return -ENODEV;
+ }
ret = pr->throttling.acpi_processor_get_throttling(pr);
/* restore the previous state */
set_cpus_allowed_ptr(current, saved_mask);
@@ -1051,6 +1055,14 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
return -ENOMEM;
}

+ if (cpu_is_offline(pr->id)) {
+ /*
+ * the cpu pointed by pr->id is offline. Unnecessary to change
+ * the throttling state any more.
+ */
+ return -ENODEV;
+ }
+
cpumask_copy(saved_mask, &current->cpus_allowed);
t_state.target_state = state;
p_throttling = &(pr->throttling);
@@ -1074,7 +1086,11 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
*/
if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
/* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(pr->id));
+ if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
+ /* Can't migrate to the pr->id CPU. Exit */
+ ret = -ENODEV;
+ goto exit;
+ }
ret = p_throttling->acpi_processor_set_throttling(pr,
t_state.target_state, force);
} else {
@@ -1106,7 +1122,8 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
}
t_state.cpu = i;
/* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(i));
+ if (set_cpus_allowed_ptr(current, cpumask_of(i)))
+ continue;
ret = match_pr->throttling.
acpi_processor_set_throttling(
match_pr, t_state.target_state, force);
@@ -1126,6 +1143,7 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
/* restore the previous state */
/* FIXME: use work_on_cpu() */
set_cpus_allowed_ptr(current, saved_mask);
+exit:
free_cpumask_var(online_throttling_cpus);
free_cpumask_var(saved_mask);
return ret;
--
1.7.4.rc1.7.g2cf08