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Subject[tip:tracing/core] tracing/events: simplify system_enable_read()
Commit-ID:  c142b15dc56ee6d55cb97a062e3c8e9c61e384c0
Gitweb: http://git.kernel.org/tip/c142b15dc56ee6d55cb97a062e3c8e9c61e384c0
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Fri, 8 May 2009 10:32:05 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 8 May 2009 14:00:36 +0200

tracing/events: simplify system_enable_read()

A smarter way to figure out the output of an enable file.

[ Impact: clean up ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A0399A5.2080603@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/trace_events.c | 40 ++++++----------------------------------
1 files changed, 6 insertions(+), 34 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 45f1099..df394bc 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -414,10 +414,11 @@ static ssize_t
system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
+ const char set_to_char[4] = { '?', '0', '1', 'X' };
const char *system = filp->private_data;
struct ftrace_event_call *call;
char buf[2];
- int set = -1;
+ int set = 0;
int ret;

mutex_lock(&event_mutex);
@@ -433,47 +434,18 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
* or if all events or cleared, or if we have
* a mixture.
*/
- if (call->enabled) {
- switch (set) {
- case -1:
- set = 1;
- break;
- case 0:
- set = 2;
- break;
- }
- } else {
- switch (set) {
- case -1:
- set = 0;
- break;
- case 1:
- set = 2;
- break;
- }
- }
+ set |= (1 << !!call->enabled);
+
/*
* If we have a mixture, no need to look further.
*/
- if (set == 2)
+ if (set == 3)
break;
}
mutex_unlock(&event_mutex);

+ buf[0] = set_to_char[set];
buf[1] = '\n';
- switch (set) {
- case 0:
- buf[0] = '0';
- break;
- case 1:
- buf[0] = '1';
- break;
- case 2:
- buf[0] = 'X';
- break;
- default:
- buf[0] = '?';
- }

ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);


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