[ 3.5.y.z extended stable ] Patch "perf: Clarify perf_cpu_context::active_pmu usage by renaming" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    perf: Clarify perf_cpu_context::active_pmu usage by renaming

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 16126543b42629272fb2e69ac4ba9dd0f157f828 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra at chello.nl>
Date: Tue, 2 Oct 2012 15:38:52 +0200
Subject: [PATCH] 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 at google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra at chello.nl>
Link: http://lkml.kernel.org/n/tip-kxyjqpfj2fn9gt7kwu5ag9ks@git.kernel.org
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Cc: Li Zefan <lizefan at huawei.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 include/linux/perf_event.h |  2 +-
 kernel/events/core.c       | 12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c65c7d1..3faf0d4 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1065,7 +1065,7 @@ 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 dd815c3..b3a6de5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4331,7 +4331,7 @@ 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);

@@ -4477,7 +4477,7 @@ 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);

@@ -4673,7 +4673,7 @@ 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);
@@ -5748,8 +5748,8 @@ 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;
 	}
 }

@@ -5885,7 +5885,7 @@ 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:
--
1.8.3.2