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Subject[34-longterm 001/179] ftrace: Only update the function code on write to filter files
Date
From: Steven Rostedt <srostedt@redhat.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
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: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/trace/ftrace.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index e28af02..7dd746c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2355,14 +2355,16 @@ ftrace_regex_release(struct inode *inode, struct file *file, int enable)
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;
}
--
1.7.9.6


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