Block device poll(2) vs kqueue(2)

[Martin Pieuchot]

Diff below fixes an incoherency between poll(2) and kqueue(2) when it
comes to non-character devices.  It makes spec_kqfilter() behaves like
spec_poll(): returns "true" when applied to any non-character device.

ok?

Index: kern/spec_vnops.c
===================================================================
RCS file: /cvs/src/sys/kern/spec_vnops.c,v
retrieving revision 1.100
diff -u -p -r1.100 spec_vnops.c
--- kern/spec_vnops.c   20 Jan 2020 23:21:55 -0000      1.100
+++ kern/spec_vnops.c   20 May 2020 09:36:48 -0000
@@ -386,11 +386,9 @@ spec_poll(void *v)
        dev_t dev;
 
        switch (ap->a_vp->v_type) {
-
        default:
                return (ap->a_events &
                    (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
-
        case VCHR:
                dev = ap->a_vp->v_rdev;
                return (*cdevsw[major(dev)].d_poll)(dev, ap->a_events, ap->a_p);
@@ -400,12 +398,17 @@ int
 spec_kqfilter(void *v)
 {
        struct vop_kqfilter_args *ap = v;
-
        dev_t dev;
 
        dev = ap->a_vp->v_rdev;
-       if (cdevsw[major(dev)].d_kqfilter)
-               return (*cdevsw[major(dev)].d_kqfilter)(dev, ap->a_kn);
+
+       switch (ap->a_vp->v_type) {
+       default:
+               return seltrue_kqfilter(dev, ap->a_kn);
+       case VCHR:
+               if (cdevsw[major(dev)].d_kqfilter)
+                       return (*cdevsw[major(dev)].d_kqfilter)(dev, ap->a_kn);
+       }
        return (EOPNOTSUPP);
 }