[007/146] ftrace: Only update the function code on write to filter files

Greg KH
2011-06-01T08:06:56Z

From: Steven Rostedt <srostedt@redhat.com>

commit 058e297d34a404caaa5ed277de15698d8dc43000 upstream.

If function tracing is enabled, a read of the filter files will
cause the call to stop_machine to update the function trace sites.
It should only call stop_machine on write.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/trace/ftrace.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2414,14 +2414,16 @@ ftrace_regex_release(struct inode *inode
ftrace_match_records(parser->buffer, parser->idx, enable);
}

- mutex_lock(&ftrace_lock);
- if (ftrace_start_up && ftrace_enabled)
- ftrace_run_update_code(FTRACE_ENABLE_CALLS);
- mutex_unlock(&ftrace_lock);
-
trace_parser_put(parser);
kfree(iter);

+ if (file->f_mode & FMODE_WRITE) {
+ mutex_lock(&ftrace_lock);
+ if (ftrace_start_up && ftrace_enabled)
+ ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+ mutex_unlock(&ftrace_lock);
+ }
+
mutex_unlock(&ftrace_regex_lock);
return 0;
}