linux-kernel - [PATCH 06/19] tracing/workqueue: turn cpu_workqueue

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Date:	Thu, 30 Apr 2009 02:27:07 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Zhao Lei <zhaolei@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tom Zanussi <tzanussi@...il.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 06/19] tracing/workqueue: turn cpu_workqueue_stats::inserted into unsigned int

struct cpu_workqueue_stats used an atomic_t to protect against
concurrent incrementation of inserted worklets. But
trace_workqueue_insertion() is already inside a section protected
by the cpu workqueue lock.

Then we can safely convert it into an unsigned int.

[ Impact: cleanup ]

Reported-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Zhao Lei <zhaolei@...fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Tom Zanussi <tzanussi@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 kernel/trace/trace_workqueue.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index 1a68b5a..7c632b9 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -20,7 +20,7 @@ struct workfunc_stats {
 
 	/* Addr of worklet's callback function */
 	work_func_t			func;
-	/* Can be inserted from interrupt or user context, need to be atomic */
+	/* Can be inserted on different workqueues, need to be atomic */
 	atomic_t			inserted;
 	/*
 	 * Don't need to be atomic, works are serialized in a single workqueue
@@ -34,8 +34,8 @@ struct cpu_workqueue_stats {
 	struct list_head            list;
 	int		            cpu;
 	pid_t			    pid;
-	/* Refer to comments of struct workfunc_stats for detail */
-	atomic_t	            inserted;
+	/* Protected by cpu workqueue lock */
+	unsigned int	            inserted;
 	unsigned int		    executed;
 	/* list of struct workfunc_stats in this workqueue */
 	struct list_head            workfunclist;
@@ -62,7 +62,7 @@ int do_workqueue_insertion(struct cpu_workqueue_stats *cws,
 {
 	struct workfunc_stats *wfstat;
 
-	atomic_inc(&cws->inserted);
+	cws->inserted++;
 
 	list_for_each_entry(wfstat, &cws->workfunclist, list)
 		if (wfstat->func == work->func)
@@ -311,7 +311,7 @@ static int workqueue_stat_show(struct seq_file *s, void *p)
 			if (tsk) {
 				seq_printf(s, "%3d %6d     %6u       %s:%d\n",
 					   cws->cpu,
-					   atomic_read(&cws->inserted),
+					   cws->inserted,
 					   cws->executed,
 					   tsk->comm,
 					   cws->pid);
-- 
1.6.2.3

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