Re: [PATCH 19/33] thermal: db8500: use match_string() helper

Yisheng Xie
2018-05-23T07:49:14Z

Hi Andy,

On 2018/5/22 6:00, Andy Shevchenko wrote:
> On Mon, May 21, 2018 at 2:57 PM, Yisheng Xie <xieyisheng1@huawei.com> wrote:
>> match_string() returns the index of an array for a matching string,
>> which can be used intead of open coded variant.
>
>> + i = match_string((const char **)trip_point->cdev_name,
>
> Casting looks ugly. You need to constify the variable itself.
When I tried to const cdev_name like:
+++ b/include/linux/platform_data/db8500_thermal.h
@@ -27,7 +27,7 @@
struct db8500_trip_point {
unsigned long temp;
enum thermal_trip_type type;
- char cdev_name[COOLING_DEV_MAX][THERMAL_NAME_LENGTH];
+ char const cdev_name[COOLING_DEV_MAX][THERMAL_NAME_LENGTH]; // const char cdev_name[COOLING_DEV_MAX][THERMAL_NAME_LENGTH] will also the same
};

The compiler will also warning:
drivers/thermal/db8500_thermal.c: In function ‘db8500_thermal_match_cdev’:
drivers/thermal/db8500_thermal.c:53:2: warning: passing argument 1 of ‘match_string’ from incompatible pointer type [enabled by default]
i = match_string(trip_point->cdev_name, COOLING_DEV_MAX, cdev->type);
^
In file included from include/linux/bitmap.h:9:0,
from include/linux/cpumask.h:12,
from include/linux/rcupdate.h:44,
from include/linux/radix-tree.h:28,
from include/linux/idr.h:15,
from include/linux/kernfs.h:14,
from include/linux/sysfs.h:16,
from kernel/include/linux/kobject.h:20,
from kernel/include/linux/of.h:17,
from include/linux/cpu_cooling.h:27,
from drivers/thermal/db8500_thermal.c:20:
include/linux/string.h:184:5: note: expected ‘const char * const*’ but argument is of type ‘const char (*)[20]’

Any idea?

Thanks
Yisheng
>
>> + COOLING_DEV_MAX, cdev->type);
>>
>> - return -ENODEV;
>> + return (i < 0) ? -ENODEV : 0;
>
> I would rather go with
>
> if (ret < 0)
> return -ENODEV;
>
> return 0;
>