[PATCH 4.19.y 07/13] tracing: Use str_has_prefix() helper for histogram code

George Guo
2024-05-09T02:30:24Z

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

commit 754481e6954cbef53f8bc4412ad48dde611e21d3 upstream.

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>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
kernel/trace/trace_events_hist.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1139075a6395..1441c3934cbf 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1878,8 +1878,8 @@ static int parse_action(char *str, struct hist_trigger_attrs *attrs)
if (attrs->n_actions >= HIST_ACTIONS_MAX)
return ret;

- if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0) ||
- (strncmp(str, "onmax(", strlen("onmax(")) == 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;
@@ -1896,34 +1896,34 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
{
int ret = 0;

- if ((strncmp(str, "key=", strlen("key=")) == 0) ||
- (strncmp(str, "keys=", strlen("keys=")) == 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=", strlen("val=")) == 0) ||
- (strncmp(str, "vals=", strlen("vals=")) == 0) ||
- (strncmp(str, "values=", strlen("values=")) == 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=", strlen("sort=")) == 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=", strlen("name=")) == 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=", strlen("clock=")) == 0) {
+ } else if (str_has_prefix(str, "clock=")) {
strsep(&str, "=");
if (!str) {
ret = -EINVAL;
@@ -1936,7 +1936,7 @@ static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
ret = -ENOMEM;
goto out;
}
- } else if (strncmp(str, "size=", strlen("size=")) == 0) {
+ } else if (str_has_prefix(str, "size=")) {
int map_bits = parse_map_size(str);

if (map_bits < 0) {
@@ -3623,7 +3623,7 @@ static struct action_data *onmax_parse(char *str)
if (!onmax_fn_name || !str)
goto free;

- if (strncmp(onmax_fn_name, "save", strlen("save")) == 0) {
+ if (str_has_prefix(onmax_fn_name, "save")) {
char *params = strsep(&str, ")");

if (!params) {
@@ -4414,8 +4414,8 @@ 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(", strlen("onmatch(")) == 0) {
- char *action_str = str + strlen("onmatch(");
+ if (str_has_prefix(str, "onmatch(")) {
+ char *action_str = str + sizeof("onmatch(") - 1;

data = onmatch_parse(tr, action_str);
if (IS_ERR(data)) {
@@ -4423,8 +4423,8 @@ static int parse_actions(struct hist_trigger_data *hist_data)
break;
}
data->fn = action_trace;
- } else if (strncmp(str, "onmax(", strlen("onmax(")) == 0) {
- char *action_str = str + strlen("onmax(");
+ } else if (str_has_prefix(str, "onmax(")) {
+ char *action_str = str + sizeof("onmax(") - 1;

data = onmax_parse(action_str);
if (IS_ERR(data)) {
--
2.34.1