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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>
Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit 2cd21fa1b54efaf6b5912ef2833fa474fdcf92b7
to fix build failure due to fed4b99)
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Peter Zijlstra authored and peat-psuwit committed Oct 2, 2012
1 parent db54ed3 commit 99bdb252098c1b926d3c851efbd70ab574d10a2c
Showing with 7 additions and 7 deletions.
  1. +1 −1 include/linux/perf_event.h
  2. +6 −6 kernel/events/core.c
@@ -1068,7 +1068,7 @@ 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;
};

@@ -4302,7 +4302,7 @@ 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);

@@ -4448,7 +4448,7 @@ 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);

@@ -4644,7 +4644,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_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_mmap_ctx(&cpuctx->ctx, mmap_event,
vma->vm_flags & VM_EXEC);
@@ -5733,8 +5733,8 @@ 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;
}
}

@@ -5869,7 +5869,7 @@ int perf_pmu_register(struct pmu *pmu, char *name, int 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:

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