Re: [PATCH 04/11] General notification queue with user mmap()'able ring buffer [ver #7]

[David Howells]

Hillf Danton <hdan...@sina.com> wrote:

> > +   for (i = 0; i < wf->nr_filters; i++) {
> > +           wt = &wf->filters[i];
> > +           if (n->type == wt->type &&
> > +               (wt->subtype_filter[n->subtype >> 5] &
> > +                (1U << (n->subtype & 31))) &&
> 
> Replace the pure numbers with something easier to understand.

How about the following:

static bool filter_watch_notification(const struct watch_filter *wf,
                                      const struct watch_notification *n)
{
        const struct watch_type_filter *wt;
        unsigned int st_bits = sizeof(wt->subtype_filter[0]) * 8;
        unsigned int st_index = n->subtype / st_bits;
        unsigned int st_bit = 1U << (n->subtype % st_bits);
        int i;

        if (!test_bit(n->type, wf->type_filter))
                return false;

        for (i = 0; i < wf->nr_filters; i++) {
                wt = &wf->filters[i];
                if (n->type == wt->type &&
                    (wt->subtype_filter[st_index] & st_bit) &&
                    (n->info & wt->info_mask) == wt->info_filter)
                        return true;
        }

        return false; /* If there is a filter, the default is to reject. */
}

David