tracing: Use str_has_prefix() helper for histogram code

The tracing histogram code contains a lot of instances of the construct:

 strncmp(str, "const", sizeof("const") - 1)

This can be prone to bugs due to typos or bad cut and paste. Use the
str_has_prefix() helper macro instead that removes the need for having two
copies of the constant string.

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c5448c103770a5aeeb505024bac41ce3dfefc900..9d590138f870e4b7d6b5061d9088667bd8604e7b 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1881,8 +1881,8 @@ static int parse_action(char *str, struct hist_trigger_attrs *attrs)
        if (attrs->n_actions >= HIST_ACTIONS_MAX)
                return ret;
 
-       if ((strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) ||
-           (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0)) {
+       if ((str_has_prefix(str, "onmatch(")) ||
+           (str_has_prefix(str, "onmax("))) {
                attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
                if (!attrs->action_str[attrs->n_actions]) {
                        ret = -ENOMEM;
@@ -1899,34 +1899,34 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
 {
        int ret = 0;
 
-       if ((strncmp(str, "key=", sizeof("key=") - 1) == 0) ||
-           (strncmp(str, "keys=", sizeof("keys=") - 1) == 0)) {
+       if ((str_has_prefix(str, "key=")) ||
+           (str_has_prefix(str, "keys="))) {
                attrs->keys_str = kstrdup(str, GFP_KERNEL);
                if (!attrs->keys_str) {
                        ret = -ENOMEM;
                        goto out;
                }
-       } else if ((strncmp(str, "val=", sizeof("val=") - 1) == 0) ||
-                (strncmp(str, "vals=", sizeof("vals=") - 1) == 0) ||
-                (strncmp(str, "values=", sizeof("values=") - 1) == 0)) {
+       } else if ((str_has_prefix(str, "val=")) ||
+                  (str_has_prefix(str, "vals=")) ||
+                  (str_has_prefix(str, "values="))) {
                attrs->vals_str = kstrdup(str, GFP_KERNEL);
                if (!attrs->vals_str) {
                        ret = -ENOMEM;
                        goto out;
                }
-       } else if (strncmp(str, "sort=", sizeof("sort=") - 1) == 0) {
+       } else if (str_has_prefix(str, "sort=")) {
                attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
                if (!attrs->sort_key_str) {
                        ret = -ENOMEM;
                        goto out;
                }
-       } else if (strncmp(str, "name=", sizeof("name=") - 1) == 0) {
+       } else if (str_has_prefix(str, "name=")) {
                attrs->name = kstrdup(str, GFP_KERNEL);
                if (!attrs->name) {
                        ret = -ENOMEM;
                        goto out;
                }
-       } else if (strncmp(str, "clock=", sizeof("clock=") - 1) == 0) {
+       } else if (str_has_prefix(str, "clock=")) {
                strsep(&str, "=");
                if (!str) {
                        ret = -EINVAL;
@@ -1939,7 +1939,7 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
                        ret = -ENOMEM;
                        goto out;
                }
-       } else if (strncmp(str, "size=", sizeof("size=") - 1) == 0) {
+       } else if (str_has_prefix(str, "size=")) {
                int map_bits = parse_map_size(str);
 
                if (map_bits < 0) {
@@ -3558,7 +3558,7 @@ static struct action_data *onmax_parse(char *str)
        if (!onmax_fn_name || !str)
                goto free;
 
-       if (strncmp(onmax_fn_name, "save", sizeof("save") - 1) == 0) {
+       if (str_has_prefix(onmax_fn_name, "save")) {
                char *params = strsep(&str, ")");
 
                if (!params) {
@@ -4346,7 +4346,7 @@ static int parse_actions(struct hist_trigger_data *hist_data)
        for (i = 0; i < hist_data->attrs->n_actions; i++) {
                str = hist_data->attrs->action_str[i];
 
-               if (strncmp(str, "onmatch(", sizeof("onmatch(") - 1) == 0) {
+               if (str_has_prefix(str, "onmatch(")) {
                        char *action_str = str + sizeof("onmatch(") - 1;
 
                        data = onmatch_parse(tr, action_str);
@@ -4355,7 +4355,7 @@ static int parse_actions(struct hist_trigger_data *hist_data)
                                break;
                        }
                        data->fn = action_trace;
-               } else if (strncmp(str, "onmax(", sizeof("onmax(") - 1) == 0) {
+               } else if (str_has_prefix(str, "onmax(")) {
                        char *action_str = str + sizeof("onmax(") - 1;
 
                        data = onmax_parse(action_str);