Modifying a knote must be done with the corresponding lock held. Assert

that the KERNEL_LOCK() is held unless the filter is marked as MPSAFE.

Should help finding missing locks when unlocking various filters.

ok visa@

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 370a8f6..030b20e 100644 (file)
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_event.c,v 1.168 2021/07/22 07:22:43 visa Exp $   */
+/*     $OpenBSD: kern_event.c,v 1.169 2021/07/24 09:16:51 mpi Exp $    */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -1908,6 +1908,9 @@ knote_dequeue(struct knote *kn)
 void
 knote_modify(const struct kevent *kev, struct knote *kn)
 {
+       if ((kn->kn_fop->f_flags & FILTEROP_MPSAFE) == 0)
+               KERNEL_ASSERT_LOCKED();
+
        kn->kn_sfflags = kev->fflags;
        kn->kn_sdata = kev->data;
        kn->kn_udata = kev->udata;
@@ -1921,6 +1924,9 @@ knote_modify(const struct kevent *kev, struct knote *kn)
 void
 knote_submit(struct knote *kn, struct kevent *kev)
 {
+       if ((kn->kn_fop->f_flags & FILTEROP_MPSAFE) == 0)
+               KERNEL_ASSERT_LOCKED();
+
        if (kev != NULL) {
                *kev = kn->kn_kevent;
                if (kn->kn_flags & EV_CLEAR) {