Re: [net-next v4 3/3] selftests/sysctl: add sysctl macro test

[Tonghao Zhang <xiangxia.m.yue@gmail.com>]

On Tue, Apr 26, 2022 at 3:58 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Fri, 22 Apr 2022 15:01:41 +0800 xiangxia.m.yue@gmail.com wrote:
> >  static int __init test_sysctl_init(void)
> >  {
> > +     test_data.match_int[0] = *(int *)SYSCTL_ZERO,
> > +     test_data.match_int[1] = *(int *)SYSCTL_ONE,
> > +     test_data.match_int[2] = *(int *)SYSCTL_TWO,
> > +     test_data.match_int[3] = *(int *)SYSCTL_THREE,
> > +     test_data.match_int[4] = *(int *)SYSCTL_FOUR,
> > +     test_data.match_int[5] = *(int *)SYSCTL_ONE_HUNDRED,
> > +     test_data.match_int[6] = *(int *)SYSCTL_TWO_HUNDRED,
> > +     test_data.match_int[7] = *(int *)SYSCTL_ONE_THOUSAND,
> > +     test_data.match_int[8] = *(int *)SYSCTL_THREE_THOUSAND,
> > +     test_data.match_int[9] = *(int *)SYSCTL_INT_MAX,
> > +     test_data.match_int[10] = *(int *)SYSCTL_MAXOLDUID,
> > +     test_data.match_int[11] = *(int *)SYSCTL_NEG_ONE,
>
> > +     local VALUES=(0 1 2 3 4 100 200 1000 3000 $INT_MAX 65535 -1)
>
> How does this test work? Am I reading it right that it checks if this
> bash array is in sync with the kernel code?
This patch tries to avoid SYSCTL_XXX not mapping the values we hoped,
when introducing the new SYSCTL_YYY.
for example:
SYSCTL_TWO, we hope it is 2, so we check it in userspace.
> I'd be better if we were checking the values of the constants against
> literals / defines.
Hi Jakub, I think this patch checks the values of the constants
against defines. But I should make the codes more readable

 static int __init test_sysctl_init(void)
 {
+       int i;
+
+       struct {
+               int defined;
+               int wanted;
+       } match_int[] = {
+               {.defined = *(int *)SYSCTL_ZERO,        .wanted = 0},
+               {.defined = *(int *)SYSCTL_ONE,         .wanted = 1},
+               {.defined = *(int *)SYSCTL_TWO,         .wanted = 2},
+               {.defined = *(int *)SYSCTL_THREE,       .wanted = 3},
+               {.defined = *(int *)SYSCTL_FOUR,        .wanted = 4},
+               {.defined = *(int *)SYSCTL_ONE_HUNDRED, .wanted = 100},
+               {.defined = *(int *)SYSCTL_TWO_HUNDRED, .wanted = 200},
+               {.defined = *(int *)SYSCTL_ONE_THOUSAND, .wanted = 1000},
+               {.defined = *(int *)SYSCTL_THREE_THOUSAND, .wanted = 3000},
+               {.defined = *(int *)SYSCTL_INT_MAX,     .wanted = INT_MAX},
+               {.defined = *(int *)SYSCTL_MAXOLDUID,   .wanted = 65535},
+               {.defined = *(int *)SYSCTL_NEG_ONE,     .wanted = -1},
+       };
+
+       for (i = 0; i < ARRAY_SIZE(match_int); i++)
+               if (match_int[i].defined != match_int[i].wanted)
+                       match_int_ok = 0;
+




--
Best regards, Tonghao