Translate POLLNVAL in ppollcollect()

This makes the kqueue-based poll(2) behave more similarly to the old
code when a monitored file descriptor is closed by another thread.

OK mpi@

diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 3a44978..59a003a 100644 (file)
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: sys_generic.c,v 1.141 2021/11/16 13:48:23 visa Exp $  */
+/*     $OpenBSD: sys_generic.c,v 1.142 2021/11/22 14:59:03 visa Exp $  */
 /*     $NetBSD: sys_generic.c,v 1.24 1996/03/29 00:25:32 cgd Exp $     */
 
 /*
@@ -1263,6 +1263,14 @@ ppollcollect(struct proc *p, struct kevent *kevp, struct pollfd *pl, u_int nfds)
         */
        already_seen = (pl[i].revents != 0);
 
+       /* POLLNVAL preempts other events. */
+       if ((kevp->flags & EV_ERROR) && kevp->data == EBADF) {
+               pl[i].revents = POLLNVAL;
+               goto done;
+       } else if (pl[i].revents & POLLNVAL) {
+               goto done;
+       }
+
        switch (kevp->filter) {
        case EVFILT_READ:
                if (kevp->flags & __EV_HUP)
@@ -1294,6 +1302,7 @@ ppollcollect(struct proc *p, struct kevent *kevp, struct pollfd *pl, u_int nfds)
                KASSERT(0);
        }
 
+done:
        DPRINTFN(1, "poll get %lu/%d fd %d revents %02x serial %lu filt %d\n",
            i+1, nfds, pl[i].fd, pl[i].revents, (unsigned long)kevp->udata,
            kevp->filter);