[PATCH] cpufreq: warn about invalid vals to scaling_max/min_freq interfaces

[qinyu <qinyu32@huawei.com>]

When echo an invalid val to scaling_min_freq:
> echo 123abc123 > scaling_min_freq
It looks weird to have a return val of 0:
> echo $?
> 0

Sane people won't echo strings like that into these interfaces but fuzz
tests may do. Also, maybe it's better to inform people if input is invalid
or out of range.

After this:
> echo 123abc123 > scaling_min_freq
> -bash: echo: write error: Invalid argument

Signed-off-by: qinyu <qinyu32@huawei.com>
Tested-by: zhangxiaofeng <zhangxiaofeng46@huawei.com>
---
 drivers/cpufreq/cpufreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 6d8fd3b8d..d61f7308f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -725,9 +725,9 @@ static ssize_t store_##file_name					\
 	unsigned long val;						\
 	int ret;							\
 									\
-	ret = sscanf(buf, "%lu", &val);					\
-	if (ret != 1)							\
-		return -EINVAL;						\
+	ret = kstrtoul(buf, 0, &val);					\
+	if (ret)							\
+		return ret;						\
 									\
 	ret = freq_qos_update_request(policy->object##_freq_req, val);\
 	return ret >= 0 ? count : ret;					\
-- 
2.33.0