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Subject[PATCH 3.8 68/81] ACPI / processor: Rework processor throttling with work_on_cpu()
Date
3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lan Tianyu <tianyu.lan@intel.com>

commit f3ca4164529b875374c410193bbbac0ee960895f upstream.

acpi_processor_set_throttling() uses set_cpus_allowed_ptr() to make
sure that the (struct acpi_processor)->acpi_processor_set_throttling()
callback will run on the right CPU. However, the function may be
called from a worker thread already bound to a different CPU in which
case that won't work.

Make acpi_processor_set_throttling() use work_on_cpu() as appropriate
instead of abusing set_cpus_allowed_ptr().

Reported-and-tested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/acpi/processor_throttling.c | 69 +++++++++++++++++--------------------
1 file changed, 32 insertions(+), 37 deletions(-)

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index 1d02b7b..c653cc2 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -59,6 +59,12 @@ struct throttling_tstate {
int target_state; /* target T-state */
};

+struct acpi_processor_throttling_arg {
+ struct acpi_processor *pr;
+ int target_state;
+ bool force;
+};
+
#define THROTTLING_PRECHANGE (1)
#define THROTTLING_POSTCHANGE (2)

@@ -1062,16 +1068,24 @@ static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
return 0;
}

+static long acpi_processor_throttling_fn(void *data)
+{
+ struct acpi_processor_throttling_arg *arg = data;
+ struct acpi_processor *pr = arg->pr;
+
+ return pr->throttling.acpi_processor_set_throttling(pr,
+ arg->target_state, arg->force);
+}
+
int acpi_processor_set_throttling(struct acpi_processor *pr,
int state, bool force)
{
- cpumask_var_t saved_mask;
int ret = 0;
unsigned int i;
struct acpi_processor *match_pr;
struct acpi_processor_throttling *p_throttling;
+ struct acpi_processor_throttling_arg arg;
struct throttling_tstate t_state;
- cpumask_var_t online_throttling_cpus;

if (!pr)
return -EINVAL;
@@ -1082,14 +1096,6 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
if ((state < 0) || (state > (pr->throttling.state_count - 1)))
return -EINVAL;

- if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
- return -ENOMEM;
-
- if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
- free_cpumask_var(saved_mask);
- return -ENOMEM;
- }
-
if (cpu_is_offline(pr->id)) {
/*
* the cpu pointed by pr->id is offline. Unnecessary to change
@@ -1098,17 +1104,15 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
return -ENODEV;
}

- cpumask_copy(saved_mask, &current->cpus_allowed);
t_state.target_state = state;
p_throttling = &(pr->throttling);
- cpumask_and(online_throttling_cpus, cpu_online_mask,
- p_throttling->shared_cpu_map);
+
/*
* The throttling notifier will be called for every
* affected cpu in order to get one proper T-state.
* The notifier event is THROTTLING_PRECHANGE.
*/
- for_each_cpu(i, online_throttling_cpus) {
+ for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
t_state.cpu = i;
acpi_processor_throttling_notifier(THROTTLING_PRECHANGE,
&t_state);
@@ -1120,21 +1124,18 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
* it can be called only for the cpu pointed by pr.
*/
if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
- /* FIXME: use work_on_cpu() */
- 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);
+ arg.pr = pr;
+ arg.target_state = state;
+ arg.force = force;
+ ret = work_on_cpu(pr->id, acpi_processor_throttling_fn, &arg);
} else {
/*
* When the T-state coordination is SW_ALL or HW_ALL,
* it is necessary to set T-state for every affected
* cpus.
*/
- for_each_cpu(i, online_throttling_cpus) {
+ for_each_cpu_and(i, cpu_online_mask,
+ p_throttling->shared_cpu_map) {
match_pr = per_cpu(processors, i);
/*
* If the pointer is invalid, we will report the
@@ -1155,13 +1156,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
"on CPU %d\n", i));
continue;
}
- t_state.cpu = i;
- /* FIXME: use work_on_cpu() */
- 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);
+
+ arg.pr = match_pr;
+ arg.target_state = state;
+ arg.force = force;
+ ret = work_on_cpu(pr->id, acpi_processor_throttling_fn,
+ &arg);
}
}
/*
@@ -1170,17 +1170,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
* affected cpu to update the T-states.
* The notifier event is THROTTLING_POSTCHANGE
*/
- for_each_cpu(i, online_throttling_cpus) {
+ for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
t_state.cpu = i;
acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
&t_state);
}
- /* 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;
}

--
1.8.3.2


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