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 <[email protected]>
---
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
On Fri 2019-08-09 15:10:34, Chuhong Yuan wrote:
> 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 <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Best Regards,
Petr
On (08/14/19 12:49), Petr Mladek wrote:
> On Fri 2019-08-09 15:10:34, Chuhong Yuan wrote:
> > 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 <[email protected]>
>
> Reviewed-by: Petr Mladek <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
-ss
On Thu 2019-08-15 16:50:33, Sergey Senozhatsky wrote:
> On (08/14/19 12:49), Petr Mladek wrote:
> > On Fri 2019-08-09 15:10:34, Chuhong Yuan wrote:
> > > 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 <[email protected]>
> >
> > Reviewed-by: Petr Mladek <[email protected]>
>
> Reviewed-by: Sergey Senozhatsky <[email protected]>
Chuong Yuan, should I take this patch via printk.git? Or will
the entire series go via some other tree, please?
Best Regards,
Petr
On Thu, Aug 15, 2019 at 9:52 PM Petr Mladek <[email protected]> wrote:
>
> On Thu 2019-08-15 16:50:33, Sergey Senozhatsky wrote:
> > On (08/14/19 12:49), Petr Mladek wrote:
> > > On Fri 2019-08-09 15:10:34, Chuhong Yuan wrote:
> > > > 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 <[email protected]>
> > >
> > > Reviewed-by: Petr Mladek <[email protected]>
> >
> > Reviewed-by: Sergey Senozhatsky <[email protected]>
>
> Chuong Yuan, should I take this patch via printk.git? Or will
> the entire series go via some other tree, please?
>
I think that it goes via printk.git is okay, thanks!
> Best Regards,
> Petr
On Thu 2019-08-15 23:33:01, Chuhong Yuan wrote:
> On Thu, Aug 15, 2019 at 9:52 PM Petr Mladek <[email protected]> wrote:
> >
> > On Thu 2019-08-15 16:50:33, Sergey Senozhatsky wrote:
> > > On (08/14/19 12:49), Petr Mladek wrote:
> > > > On Fri 2019-08-09 15:10:34, Chuhong Yuan wrote:
> > > > > 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 <[email protected]>
> > > >
> > > > Reviewed-by: Petr Mladek <[email protected]>
> > >
> > > Reviewed-by: Sergey Senozhatsky <[email protected]>
> >
> > Chuong Yuan, should I take this patch via printk.git? Or will
> > the entire series go via some other tree, please?
> >
>
> I think that it goes via printk.git is okay, thanks!
The patch is commited into printk.git, branch for-5.4.
Best Regards,
Petr