[src/trunk]: src/sys Allow the f_touch() filter op to return an error, specif...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/7f1722bd9eb2
branches:  trunk
changeset: 1024377:7f1722bd9eb2
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Thu Oct 21 02:34:03 2021 +0000

description:
Allow the f_touch() filter op to return an error, specifically in
the EVENT_REGISTER case.

diffstat:

 sys/kern/kern_event.c |  27 +++++++++++++++++----------
 sys/sys/event.h       |   4 ++--
 2 files changed, 19 insertions(+), 12 deletions(-)

diffs (118 lines):

diff -r 5d1b2e82816c -r 7f1722bd9eb2 sys/kern/kern_event.c
--- a/sys/kern/kern_event.c     Thu Oct 21 01:11:21 2021 +0000
+++ b/sys/kern/kern_event.c     Thu Oct 21 02:34:03 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_event.c,v 1.134 2021/10/21 01:11:21 thorpej Exp $ */
+/*     $NetBSD: kern_event.c,v 1.135 2021/10/21 02:34:03 thorpej Exp $ */
 
 /*-
  * Copyright (c) 2008, 2009, 2021 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
 #endif /* _KERNEL_OPT */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.134 2021/10/21 01:11:21 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.135 2021/10/21 02:34:03 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -116,7 +116,7 @@
 static int     filt_userattach(struct knote *);
 static void    filt_userdetach(struct knote *);
 static int     filt_user(struct knote *, long hint);
-static void    filt_usertouch(struct knote *, struct kevent *, long type);
+static int     filt_usertouch(struct knote *, struct kevent *, long type);
 
 static const struct fileops kqueueops = {
        .fo_name = "kqueue",
@@ -476,10 +476,10 @@
        return rv;
 }
 
-static void
+static int
 filter_touch(struct knote *kn, struct kevent *kev, long type)
 {
-       kn->kn_fop->f_touch(kn, kev, type);
+       return kn->kn_fop->f_touch(kn, kev, type);
 }
 
 static kauth_listener_t        kqueue_listener;
@@ -1384,7 +1384,7 @@
        return hookid;
 }
 
-static void
+static int
 filt_usertouch(struct knote *kn, struct kevent *kev, long type)
 {
        int ffctrl;
@@ -1441,6 +1441,8 @@
                panic("filt_usertouch() - invalid type (%ld)", type);
                break;
        }
+
+       return 0;
 }
 
 /*
@@ -1874,8 +1876,13 @@
        if (!(kn->kn_fop->f_flags & FILTEROP_ISFD) &&
            kn->kn_fop->f_touch != NULL) {
                mutex_spin_enter(&kq->kq_lock);
-               filter_touch(kn, kev, EVENT_REGISTER);
+               error = filter_touch(kn, kev, EVENT_REGISTER);
                mutex_spin_exit(&kq->kq_lock);
+               if (__predict_false(error != 0)) {
+                       /* Never a new knote (which would consume newkn). */
+                       KASSERT(newkn != NULL);
+                       goto doneunlock;
+               }
        } else {
                kn->kn_sfflags = kev->fflags;
                kn->kn_sdata = kev->data;
@@ -1887,7 +1894,7 @@
         * support events, and the attach routine is
         * broken and does not return an error.
         */
-done_ev_add:
+ done_ev_add:
        rv = filter_event(kn, 0);
        if (rv)
                knote_activate(kn);
@@ -1904,7 +1911,7 @@
        if ((kev->flags & EV_ENABLE)) {
                knote_enqueue(kn);
        }
-doneunlock:
+ doneunlock:
        mutex_exit(&fdp->fd_lock);
  done:
        rw_exit(&kqueue_filter_lock);
@@ -2197,7 +2204,7 @@
                                kn->kn_fop->f_touch != NULL);
                /* XXXAD should be got from f_event if !oneshot. */
                if (touch) {
-                       filter_touch(kn, kevp, EVENT_PROCESS);
+                       (void)filter_touch(kn, kevp, EVENT_PROCESS);
                } else {
                        *kevp = kn->kn_kevent;
                }
diff -r 5d1b2e82816c -r 7f1722bd9eb2 sys/sys/event.h
--- a/sys/sys/event.h   Thu Oct 21 01:11:21 2021 +0000
+++ b/sys/sys/event.h   Thu Oct 21 02:34:03 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: event.h,v 1.49 2021/10/20 03:08:18 thorpej Exp $       */
+/*     $NetBSD: event.h,v 1.50 2021/10/21 02:34:04 thorpej Exp $       */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon%FreeBSD.org@localhost>
@@ -230,7 +230,7 @@
                                        /* called when knote is DELETEd */
        int     (*f_event)      (struct knote *, long);
                                        /* called when event is triggered */
-       void    (*f_touch)      (struct knote *, struct kevent *, long);
+       int     (*f_touch)      (struct knote *, struct kevent *, long);
 };
 
 /* filterops flags */