[PATCHv2 07/10] ftrace: Change filter/notrace set functions to return exit code

[Jiri Olsa <jolsa@redhat.com>]

Currently the ftrace_set_filter and ftrace_set_notrace functions
do not return any return code. So there's no way for ftrace_ops
user to tell wether the filter was correctly applied.

The set_ftrace_filter interface returns error in case the filter
did not match:

  # echo krava > set_ftrace_filter
  bash: echo: write error: Invalid argument

Changing both ftrace_set_filter and ftrace_set_notrace functions
to return zero if the filter was applied correctly or -E* values
in case of error.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 include/linux/ftrace.h |    4 ++--
 kernel/trace/ftrace.c  |   16 ++++++++++------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index b223944..ddd55cc 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -194,9 +194,9 @@ struct dyn_ftrace {
 };
 
 int ftrace_force_update(void);
-void ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
+int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 		       int len, int reset);
-void ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
+int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
 			int len, int reset);
 void ftrace_set_global_filter(unsigned char *buf, int len, int reset);
 void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c2fa233..2dae0c7 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2975,8 +2975,11 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
 	mutex_lock(&ftrace_regex_lock);
 	if (reset)
 		ftrace_filter_reset(hash);
-	if (buf)
-		ftrace_match_records(hash, buf, len);
+	if (buf &&
+	    !ftrace_match_records(hash, buf, len)) {
+		ret = -EINVAL;
+		goto out_regex_unlock;
+	}
 
 	mutex_lock(&ftrace_lock);
 	ret = ftrace_hash_move(ops, enable, orig_hash, hash);
@@ -2986,6 +2989,7 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
 
 	mutex_unlock(&ftrace_lock);
 
+ out_regex_unlock:
 	mutex_unlock(&ftrace_regex_lock);
 
 	free_ftrace_hash(hash);
@@ -3002,10 +3006,10 @@ ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
  * Filters denote which functions should be enabled when tracing is enabled.
  * If @buf is NULL and reset is set, all functions will be enabled for tracing.
  */
-void ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
+int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 		       int len, int reset)
 {
-	ftrace_set_regex(ops, buf, len, reset, 1);
+	return ftrace_set_regex(ops, buf, len, reset, 1);
 }
 EXPORT_SYMBOL_GPL(ftrace_set_filter);
 
@@ -3020,10 +3024,10 @@ EXPORT_SYMBOL_GPL(ftrace_set_filter);
  * is enabled. If @buf is NULL and reset is set, all functions will be enabled
  * for tracing.
  */
-void ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
+int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
 			int len, int reset)
 {
-	ftrace_set_regex(ops, buf, len, reset, 0);
+	return ftrace_set_regex(ops, buf, len, reset, 0);
 }
 EXPORT_SYMBOL_GPL(ftrace_set_notrace);
 /**
-- 
1.7.1