linux-kernel - [PATCH 1/5] tracing/ftrace: Types and naming corrections for sched tracer

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Message-ID: <48FF636F.6090804@gmail.com>
Date:	Wed, 22 Oct 2008 19:31:27 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/5] tracing/ftrace: Types and naming corrections for sched
 tracer

This patch applies some corrections suggested by Steven Rostedt.

Change the type of shed_ref into int since it is used
into a Mutex, we don't need it anymore as an atomic
variable in the sched_switch tracer.
Also change the name of the register mutex.


Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
---
 kernel/trace/trace_sched_switch.c |   30 +++++++++++++-----------------
 1 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c
b/kernel/trace/trace_sched_switch.c
index 9d7bdac..969953b 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -16,8 +16,8 @@

 static struct trace_array	*ctx_trace;
 static int __read_mostly	tracer_enabled;
-static atomic_t		sched_ref;
-static DEFINE_MUTEX(tracepoint_mutex);
+static int			sched_ref;
+static DEFINE_MUTEX(sched_register_mutex);

 static void
 probe_sched_switch(struct rq *__rq, struct task_struct *prev,
@@ -28,7 +28,7 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
 	int cpu;
 	int pc;

-	if (!atomic_read(&sched_ref))
+	if (!sched_ref)
 		return;

 	tracing_record_cmdline(prev);
@@ -124,26 +124,22 @@ static void tracing_sched_unregister(void)

 static void tracing_start_sched_switch(void)
 {
-	long ref;
-
-	mutex_lock(&tracepoint_mutex);
-	 tracer_enabled = 1;
-	ref = atomic_inc_return(&sched_ref);
-	if (ref == 1)
+	mutex_lock(&sched_register_mutex);
+	if (!(sched_ref++)) {
+		tracer_enabled = 1;
 		tracing_sched_register();
-	mutex_unlock(&tracepoint_mutex);
+	}
+	mutex_unlock(&sched_register_mutex);
 }

 static void tracing_stop_sched_switch(void)
 {
-	long ref;
-
-	mutex_lock(&tracepoint_mutex);
-	tracer_enabled = 0;
-	ref = atomic_dec_and_test(&sched_ref);
-	if (ref)
+	mutex_lock(&sched_register_mutex);
+	if (!(--sched_ref)) {
 		tracing_sched_unregister();
-	mutex_unlock(&tracepoint_mutex);
+		tracer_enabled = 0;
+	}
+	mutex_unlock(&sched_register_mutex);
 }

 void tracing_start_cmdline_record(void)
--
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