ACPI / processor: Rework processor throttling with work_on_cpu()

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 32 insertions, 37 deletions

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index e7dd2c1fee79..5e47d7bf4745 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)
 
@@ -1063,16 +1069,24 @@ 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;
@@ -1083,14 +1097,6 @@ 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
@@ -1099,17 +1105,15 @@ 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);
@@ -1121,21 +1125,18 @@ 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
@@ -1156,13 +1157,12 @@ 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);
                 }
         }
         /*
@@ -1171,17 +1171,12 @@ 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;
 }