I tried to echo an invalid value to an unsigned long type sysctl on 4.9.0-rc6:
linux:~# cat /proc/sys/vm/user_reserve_kbytes
131072
linux:~# echo -1 > /proc/sys/vm/user_reserve_kbytes
linux:~# cat /proc/sys/vm/user_reserve_kbytes
131072
The echo operation got error and the value do not write to user_reserve_kbytes,
however, user do not know it until check the value again.
Is it more suitable to return -EINVAL when echo an invalid value to an unsigned
long
type sysctl, in order to let user know what happened without checking its value
once more?
Just as what int type sysctl do:
linux:~#cat /proc/sys/kernel/sysctl_writes_strict
1
linux:~# echo 3 > /proc/sys/kernel/sysctl_writes_strict
bash: echo: write error: Invalid argument
----------------------
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 706309f..40e9285 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2485,10 +2485,14 @@ static int __do_proc_doulongvec_minmax(void *data,
struct ctl_table *table, int
sizeof(proc_wspace_sep), NULL);
if (err)
break;
- if (neg)
- continue;
- if ((min && val < *min) || (max && val > *max))
- continue;
+ if (neg) {
+ err = -EINVAL;
+ break;
+ }
+ if ((min && val < *min) || (max && val > *max)) {
+ err = -EINVAL;
+ break;
+ }
*i = val;
} else {
val = convdiv * (*i) / convmul;
