ACPI / processor: Rework processor throttling with work_on_cpu()

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>
Cc: All applicable <stable@vger.kernel.org>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index 28baa05b8018dd6c6e6e1db93c1a5ceed74d4d74..84243c32e29c515381634b6e7b2cc6f4d219635b 100644 (file)
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -56,6 +56,12 @@ 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)
 
@@ -1060,16 +1066,24 @@ 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;
@@ -1080,14 +1094,6 @@ 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
@@ -1096,17 +1102,15 @@ 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);
@@ -1118,21 +1122,18 @@ 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
@@ -1153,13 +1154,12 @@ 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);
                }
        }
        /*
@@ -1168,17 +1168,12 @@ 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;
 }