From: Chuhong Yuan <hslester96@gmail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, Chuhong Yuan <hslester96@gmail.com>
Subject: [PATCH v4 4/8] printk: Replace strncmp with str_has_prefix
Date: Fri, 9 Aug 2019 15:10:34 +0800 [thread overview]
Message-ID: <20190809071034.17279-1-hslester96@gmail.com> (raw)
strncmp(str, const, len) is error-prone because len
is easy to have typo.
The example is the hard-coded len has counting error
or sizeof(const) forgets - 1.
So we prefer using newly introduced str_has_prefix()
to substitute such strncmp to make code better.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
Changes in v4:
- Eliminate assignments in if conditions.
kernel/printk/braille.c | 15 +++++++++++----
kernel/printk/printk.c | 22 ++++++++++++++++------
2 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c
index 1d21ebacfdb8..17a9591e54ff 100644
--- a/kernel/printk/braille.c
+++ b/kernel/printk/braille.c
@@ -11,11 +11,18 @@
int _braille_console_setup(char **str, char **brl_options)
{
- if (!strncmp(*str, "brl,", 4)) {
+ size_t len;
+
+ len = str_has_prefix(*str, "brl,");
+ if (len) {
*brl_options = "";
- *str += 4;
- } else if (!strncmp(*str, "brl=", 4)) {
- *brl_options = *str + 4;
+ *str += len;
+ return 0;
+ }
+
+ len = str_has_prefix(*str, "brl=");
+ if (len) {
+ *brl_options = *str + len;
*str = strchr(*brl_options, ',');
if (!*str) {
pr_err("need port name after brl=\n");
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 1888f6a3b694..43a31015ec93 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -118,19 +118,29 @@ static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
static int __control_devkmsg(char *str)
{
+ size_t len;
+
if (!str)
return -EINVAL;
- if (!strncmp(str, "on", 2)) {
+ len = str_has_prefix(str, "on");
+ if (len) {
devkmsg_log = DEVKMSG_LOG_MASK_ON;
- return 2;
- } else if (!strncmp(str, "off", 3)) {
+ return len;
+ }
+
+ len = str_has_prefix(str, "off");
+ if (len) {
devkmsg_log = DEVKMSG_LOG_MASK_OFF;
- return 3;
- } else if (!strncmp(str, "ratelimit", 9)) {
+ return len;
+ }
+
+ len = str_has_prefix(str, "ratelimit");
+ if (len) {
devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
- return 9;
+ return len;
}
+
return -EINVAL;
}
--
2.20.1
next reply other threads:[~2019-08-09 7:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 7:10 Chuhong Yuan [this message]
2019-08-14 10:49 ` [PATCH v4 4/8] printk: Replace strncmp with str_has_prefix Petr Mladek
2019-08-15 7:50 ` Sergey Senozhatsky
2019-08-15 13:52 ` Petr Mladek
2019-08-15 15:33 ` Chuhong Yuan
2019-08-16 8:27 ` Petr Mladek
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