perf: Clarify perf_cpu_context::active_pmu usage by renaming it to ::unique_pmu

commit 3f1f33206c16c7b3839d71372bc2ac3f305aa802 upstream.

Stephane thought the perf_cpu_context::active_pmu name confusing and
suggested using 'unique_pmu' instead.

This pointer is a pointer to a 'random' pmu sharing the cpuctx
instance, therefore limiting a for_each_pmu loop to those where
cpuctx->unique_pmu matches the pmu we get a loop over unique cpuctx
instances.

Suggested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-kxyjqpfj2fn9gt7kwu5ag9ks@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3cfcfea..eeb6a29 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -927,7 +927,7 @@ struct perf_cpu_context {
        int                             exclusive;
        struct list_head                rotation_list;
        int                             jiffies_interval;
-       struct pmu                      *active_pmu;
+       struct pmu                      *unique_pmu;
        struct perf_cgroup              *cgrp;
 };
 

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0607487..2c3ff45 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4381,7 +4381,7 @@ static void perf_event_task_event(struct perf_task_event *task_event)
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
-               if (cpuctx->active_pmu != pmu)
+               if (cpuctx->unique_pmu != pmu)
                        goto next;
                perf_event_task_ctx(&cpuctx->ctx, task_event);
 
@@ -4527,7 +4527,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
-               if (cpuctx->active_pmu != pmu)
+               if (cpuctx->unique_pmu != pmu)
                        goto next;
                perf_event_comm_ctx(&cpuctx->ctx, comm_event);
 
@@ -4723,7 +4723,7 @@ got_name:
        rcu_read_lock();
        list_for_each_entry_rcu(pmu, &pmus, entry) {
                cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
-               if (cpuctx->active_pmu != pmu)
+               if (cpuctx->unique_pmu != pmu)
                        goto next;
                perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
                                        vma->vm_flags & VM_EXEC);
@@ -5745,8 +5745,8 @@ static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
 
                cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
 
-               if (cpuctx->active_pmu == old_pmu)
-                       cpuctx->active_pmu = pmu;
+               if (cpuctx->unique_pmu == old_pmu)
+                       cpuctx->unique_pmu = pmu;
        }
 }
 
@@ -5881,7 +5881,7 @@ skip_type:
                cpuctx->ctx.pmu = pmu;
                cpuctx->jiffies_interval = 1;
                INIT_LIST_HEAD(&cpuctx->rotation_list);
-               cpuctx->active_pmu = pmu;
+               cpuctx->unique_pmu = pmu;
        }
 
 got_cpu_context: