[src/trunk]: src/tests/kernel/kqueue The knotes for EVFILT_SIGNAL and EVFILT_...

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

details:   https://anonhg.NetBSD.org/src/rev/641aafbb3cc0
branches:  trunk
changeset: 989041:641aafbb3cc0
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sun Oct 10 18:11:31 2021 +0000

description:
The knotes for EVFILT_SIGNAL and EVFILT_PROC are maintained on a single
per-process list, and kern_event.c,v 1.129 has several KASSERT()s in
various code paths that process this list related to the mixing of these
two knote types.  This new unit test is designed specifically to exercise
those KASSERT()s and thus validate their assumptions.

diffstat:

 tests/kernel/kqueue/t_sig.c |  84 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 81 insertions(+), 3 deletions(-)

diffs (110 lines):

diff -r a54189e72d46 -r 641aafbb3cc0 tests/kernel/kqueue/t_sig.c
--- a/tests/kernel/kqueue/t_sig.c       Sun Oct 10 18:08:12 2021 +0000
+++ b/tests/kernel/kqueue/t_sig.c       Sun Oct 10 18:11:31 2021 +0000
@@ -1,7 +1,7 @@
-/* $NetBSD: t_sig.c,v 1.3 2017/01/13 21:30:41 christos Exp $ */
+/* $NetBSD: t_sig.c,v 1.4 2021/10/10 18:11:31 thorpej Exp $ */
 
 /*-
- * Copyright (c) 2002, 2008 The NetBSD Foundation, Inc.
+ * Copyright (c) 2002, 2008, 2021 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -32,7 +32,7 @@
 #include <sys/cdefs.h>
 __COPYRIGHT("@(#) Copyright (c) 2008\
  The NetBSD Foundation, inc. All rights reserved.");
-__RCSID("$NetBSD: t_sig.c,v 1.3 2017/01/13 21:30:41 christos Exp $");
+__RCSID("$NetBSD: t_sig.c,v 1.4 2021/10/10 18:11:31 thorpej Exp $");
 
 #include <sys/event.h>
 #include <sys/ioctl.h>
@@ -125,9 +125,87 @@
        (void)printf("sig: finished successfully\n");
 }
 
+/*
+ * This test case exercises code paths in the kernel that KASSERT()
+ * some assumptions about EVFILT_SIGNAL and EVFILT_PROC implementation
+ * details.
+ */
+ATF_TC(sig_and_proc);
+ATF_TC_HEAD(sig_and_proc, tc)
+{
+       atf_tc_set_md_var(tc, "descr",
+           "Validates implementation detail assumptions about "
+           "EVFILT_SIGNAL and EVFILT_PROC");
+}
+ATF_TC_BODY(sig_and_proc, tc)
+{
+       struct kevent events[3];
+       pid_t pid;
+       int kq;
+
+       pid = fork();
+       ATF_REQUIRE(pid != -1);
+
+       if (pid == 0) {
+               /*
+                * Child: create a kqueue and attach signal knotes
+                * to curproc->p_klist.
+                */
+               kq = kqueue();
+               ATF_REQUIRE(kq >= 0);
+
+               ATF_REQUIRE(signal(SIGUSR1, SIG_IGN) != SIG_ERR);
+               ATF_REQUIRE(signal(SIGUSR2, SIG_IGN) != SIG_ERR);
+
+               EV_SET(&events[0], SIGUSR1, EVFILT_SIGNAL, EV_ADD, 0, 0, NULL);
+               EV_SET(&events[1], SIGUSR2, EVFILT_SIGNAL, EV_ADD, 0, 0, NULL);
+
+               ATF_REQUIRE(kevent(kq, events, 2, &events[2], 1, NULL) == 1);
+               ATF_REQUIRE(events[2].filter == EVFILT_SIGNAL);
+               ATF_REQUIRE(events[2].ident == SIGUSR1);
+
+               /*
+                * When we exit here, the kernel will close all of
+                * its file descriptors (including our kq), which
+                * will in turn remove the signal notes from
+                * curproc->p_klist.
+                *
+                * Then, later on, the kernel will post a NOTE_EXIT
+                * on our parent's kqueue using the proc note that
+                * our parent attached to (our) curproc->p_klist.
+                * That code path KASSERT()s that the signal knotes
+                * have already been removed.
+                */
+               _exit(0);
+       }
+
+       /*
+        * Parent: create a kqueue and attach a proc note to
+        * child->p_klist.
+        */
+       kq = kqueue();
+       ATF_REQUIRE(kq >= 0);
+
+       EV_SET(&events[0], pid, EVFILT_PROC, EV_ADD, NOTE_EXIT, 0, NULL);
+
+       ATF_REQUIRE(kevent(kq, events, 1, NULL, 0, NULL) == 0);
+
+       /* Ensure we never see stale data. */
+       memset(events, 0, sizeof(events));
+
+       /* Signal child to exit. */
+       ATF_REQUIRE(kill(pid, SIGUSR1) == 0);
+
+       ATF_REQUIRE(kevent(kq, NULL, 0, events, 1, NULL) == 1);
+       ATF_REQUIRE(events[0].filter == EVFILT_PROC);
+       ATF_REQUIRE(events[0].ident == (uintptr_t)pid);
+       ATF_REQUIRE(events[0].fflags = NOTE_EXIT);
+}
+
 ATF_TP_ADD_TCS(tp)
 {
        ATF_TP_ADD_TC(tp, sig);
+       ATF_TP_ADD_TC(tp, sig_and_proc);
 
        return atf_no_error();
 }