linux-kernel - [ 12/17] perf: Clarify perf_cpu_context::active_pmu usage by renaming it to ::unique

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Message-Id: <20130929190757.981485725@linuxfoundation.org>
Date:	Sun, 29 Sep 2013 12:26:51 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Stephane Eranian <eranian@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>, Li Zefan <lizefan@...wei.com>
Subject: [ 12/17] perf: Clarify perf_cpu_context::active_pmu usage by renaming it to ::unique_pmu

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <a.p.zijlstra@...llo.nl>

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@...gle.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/n/tip-kxyjqpfj2fn9gt7kwu5ag9ks@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Li Zefan <lizefan@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/linux/perf_event.h |    2 +-
 kernel/events/core.c       |   12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -939,7 +939,7 @@ 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;
 };
 
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4579,7 +4579,7 @@ static void perf_event_task_event(struct
 	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);
 
@@ -4725,7 +4725,7 @@ static void perf_event_comm_event(struct
 	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);
 
@@ -4921,7 +4921,7 @@ 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);
@@ -5947,8 +5947,8 @@ static void update_pmu_context(struct pm
 
 		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;
 	}
 }
 
@@ -6080,7 +6080,7 @@ 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:


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