Re: [PATCH] lib: interval_tree_test: validate benchmark parameters

[Samuel Moelius]

On Tue, Jun 9, 2026 at 9:13 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue,  9 Jun 2026 00:54:47 +0000 Samuel Moelius <sam.moelius@xxxxxxxxxxxxxxx> wrote:
>
> > The interval tree runtime test accepts module parameters that are later
> > used as divisors while generating randomized intervals and while
> > reporting average timings. For example, max_endpoint=1 makes the
> > generated interval end value zero and the next modulo operation divides
> > by that zero value.
> >
> > Reject non-positive counts and require max_endpoint to provide at least
> > one non-zero generated endpoint before the test allocates state or
> > starts the benchmark.
>
> That makes sense, thanks.
>
> > --- a/lib/interval_tree_test.c
> > +++ b/lib/interval_tree_test.c
> > @@ -311,6 +311,27 @@ static inline int span_iteration_check(void) {return 0; }
> >
> >  static int interval_tree_test_init(void)
> >  {
> > +     if (nnodes <= 0) {
> > +             pr_warn("nnodes must be positive\n");
> > +             return -EINVAL;
> > +     }
> > +     if (nsearches <= 0) {
> > +             pr_warn("nsearches must be positive\n");
> > +             return -EINVAL;
> > +     }
> > +     if (perf_loops <= 0) {
> > +             pr_warn("perf_loops must be positive\n");
> > +             return -EINVAL;
> > +     }
> > +     if (search_loops <= 0) {
> > +             pr_warn("search_loops must be positive\n");
> > +             return -EINVAL;
> > +     }
> > +     if (max_endpoint < 2) {
> > +             pr_warn("max_endpoint must be at least 2\n");
> > +             return -EINVAL;
> > +     }
> > +
> >       nodes = kmalloc_objs(struct interval_tree_node, nnodes);
> >       if (!nodes)
> >               return -ENOMEM;
>
> Perhaps this can be done within the __param macro:
>
> #define __param(type, name, init, msg)                                  \
>         static type name = init;                                        \
>         module_param(name, type, 0444);                                 \
>         if (name <= 0) {                                                \
>                 pr_warn(__stringify(name) " must be positive\n");       \
>                 name = init;                                            \
>         }                                                               \
>         MODULE_PARM_DESC(name, msg);
>
> I'll add your patch as-is.  If you prefer the above approach, please send
> along a replacement patch.

I looked at this, but it would seem to require a more complicated
__param macro. For example, max_endpoint must be 2 or more. Also, the
macro would need to emit a checking function.

If it's okay, I would like to please go with this patch.