[PATCH 4.19 12/18] tracing: Have the historgram use the result of str_has_prefix() for len of prefix

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

commit 036876fa56204ae0fa59045bd6bbb2691a060633 upstream.

As str_has_prefix() returns the length on match, we can use that for the
updating of the string pointer instead of recalculating the prefix size.

Cc: Tom Zanussi  <zanussi@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/trace/trace_events_hist.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4410,12 +4410,13 @@ static int parse_actions(struct hist_tri
 	unsigned int i;
 	int ret = 0;
 	char *str;
+	int len;
 
 	for (i = 0; i < hist_data->attrs->n_actions; i++) {
 		str = hist_data->attrs->action_str[i];
 
-		if (str_has_prefix(str, "onmatch(")) {
-			char *action_str = str + sizeof("onmatch(") - 1;
+		if ((len = str_has_prefix(str, "onmatch("))) {
+			char *action_str = str + len;
 
 			data = onmatch_parse(tr, action_str);
 			if (IS_ERR(data)) {
@@ -4423,8 +4424,8 @@ static int parse_actions(struct hist_tri
 				break;
 			}
 			data->fn = action_trace;
-		} else if (str_has_prefix(str, "onmax(")) {
-			char *action_str = str + sizeof("onmax(") - 1;
+		} else if ((len = str_has_prefix(str, "onmax("))) {
+			char *action_str = str + len;
 
 			data = onmax_parse(action_str);
 			if (IS_ERR(data)) {