Add a regression test to detect if waiting on the I/O serialization lock

on socket buffers is interruptible or not, which detacts the regression I
introduced recently in 7-CURRENT (spotted by alfred).  This test passes
in older -CURRENT, and with the as-yet uncommitted sx_xlock_sig and
sblock fix patches.

2 files changed, 216 insertions, 0 deletions

diff --git a/tools/regression/sockets/sblock/Makefile b/tools/regression/sockets/sblock/Makefile
new file mode 100644
index 0000000..97343fc
--- /dev/null
+++ b/tools/regression/sockets/sblock/Makefile
@@ -0,0 +1,9 @@
+#
+# $FreeBSD$
+#
+
+PROG=	sblock
+NO_MAN=
+WARNS?=	2
+
+.include <bsd.prog.mk>
diff --git a/tools/regression/sockets/sblock/sblock.c b/tools/regression/sockets/sblock/sblock.c
new file mode 100644
index 0000000..a508811
--- /dev/null
+++ b/tools/regression/sockets/sblock/sblock.c
@@ -0,0 +1,207 @@
+/*-
+ * Copyright (c) 2007 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Sockets serialize I/O in each direction in order to avoid interlacing of
+ * I/O by multiple processes or threcvs recving or sending the socket.  This
+ * is done using some form of kernel lock (varies by kernel version), called
+ * "sblock" in FreeBSD.  However, to avoid unkillable processes waiting on
+ * I/O that may be entirely controlled by a remote network endpoint, that
+ * lock acquisition must be interruptible.
+ *
+ * To test this, set up a local domain stream socket pair and a set of three
+ * processes.  Two processes block in recv(), the first on sbwait (wait for
+ * I/O), and the second on the sblock waiting for the first to finish.  A
+ * third process is responsible for signalling the second process, then
+ * writing to the socket.  Depending on the error returned in the second
+ * process, we can tell whether the sblock wait was interrupted, or if
+ * instead the process only woke up when the write was performed.
+ */
+
+#include <sys/socket.h>
+
+#include <err.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static int interrupted;
+static void
+signal_handler(int signum)
+{
+
+	interrupted++;
+}
+
+/*
+ * Process that will perform a blocking recv on a UNIX domain socket.  This
+ * should return one byte of data.
+ */
+static void
+blocking_recver(int fd)
+{
+	ssize_t len;
+	char ch;
+
+	len = recv(fd, &ch, sizeof(ch), 0);
+	if (len < 0)
+		err(-1, "FAIL: blocking_recver: recv");
+	if (len == 0)
+		errx(-1, "FAIL: blocking_recver: recv: eof");
+	if (len != 1)
+		errx(-1, "FAIL: blocking_recver: recv: %d bytes", len);
+	if (interrupted)
+		errx(-1, "FAIL: blocking_recver: interrupted wrong pid");
+}
+
+/*
+ * Process that will perform a locking recv on a UNIX domain socket.
+ *
+ * This is where we figure out if the test worked or not.  If it has failed,
+ * then recv() will return EOF, as the close() arrives before the signal,
+ * meaning that the wait for the sblock was not interrupted; if it has
+ * succeeded, we get EINTR as the signal interrupts the lock request.
+ */
+static void
+locking_recver(int fd)
+{
+	ssize_t len;
+	char ch;
+
+	if (sleep(1) < 0)
+		err(-1, "FAIL: locking_recver: sleep");
+	len = recv(fd, &ch, sizeof(ch), 0);
+	if (len < 0 && errno != EINTR)
+		err(-1, "FAIL: locking_recver: recv");
+	if (len < 0 && errno == EINTR) {
+		fprintf(stderr, "PASS\n");
+		exit(0);
+	}
+	if (len == 0)
+		errx(-1, "FAIL: locking_recver: recv: eof");
+	if (!interrupted)
+		errx(-1, "FAIL: locking_recver: not interrupted");
+}
+
+static void
+signaller(pid_t locking_recver_pid, int fd)
+{
+	ssize_t len;
+	char ch;
+
+	if (sleep(2) < 0) {
+		warn("signaller sleep(2)");
+		return;
+	}
+	if (kill(locking_recver_pid, SIGHUP) < 0) {
+		warn("signaller kill(%d)", locking_recver_pid);
+		return;
+	}
+	if (sleep(1) < 0) {
+		warn("signaller sleep(1)");
+		return;
+	}
+	len = send(fd, &ch, sizeof(ch), 0);
+	if (len < 0) {
+		warn("signaller send");
+		return;
+	}
+	if (len != sizeof(ch)) {
+		warnx("signaller send ret %d", len);
+		return;
+	}
+	if (close(fd) < 0) {
+		warn("signaller close");
+		return;
+	}
+	if (sleep(1) < 0) {
+		warn("signaller sleep(1)");
+		return;
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+	int error, fds[2], recver_fd, sender_fd;
+	pid_t blocking_recver_pid;
+	pid_t locking_recver_pid;
+	struct sigaction sa;
+
+	if (sigaction(SIGHUP, NULL, &sa) < 0)
+		err(-1, "FAIL: sigaction(SIGHUP, NULL, &sa)");
+
+	sa.sa_handler = signal_handler;
+	if (sa.sa_flags & SA_RESTART)
+		printf("SIGHUP restartable by default (cleared)\n");
+	sa.sa_flags &= ~SA_RESTART;
+
+	if (sigaction(SIGHUP, &sa, NULL) < 0)
+		err(-1, "FAIL: sigaction(SIGHUP, &sa, NULL)");
+
+#if 0
+	if (signal(SIGHUP, signal_handler) == SIG_ERR)
+		err(-1, "FAIL: signal(SIGHUP)");
+#endif
+
+	if (socketpair(PF_LOCAL, SOCK_STREAM, 0, fds) < 0)
+		err(-1, "FAIL: socketpair(PF_LOCAL, SOGK_STREAM, 0)");
+
+	sender_fd = fds[0];
+	recver_fd = fds[1];
+
+	blocking_recver_pid = fork();
+	if (blocking_recver_pid < 0)
+		err(-1, "FAIL: fork");
+	if (blocking_recver_pid == 0) {
+		close(sender_fd);
+		blocking_recver(recver_fd);
+		exit(0);
+	}
+
+	locking_recver_pid = fork();
+	if (locking_recver_pid < 0) {
+		error = errno;
+		kill(blocking_recver_pid, SIGKILL);
+		errno = error;
+		err(-1, "FAIL: fork");
+	}
+	if (locking_recver_pid == 0) {
+		close(sender_fd);
+		locking_recver(recver_fd);
+		exit(0);
+	}
+
+	signaller(locking_recver_pid, sender_fd);
+
+	kill(blocking_recver_pid, SIGKILL);
+	kill(locking_recver_pid, SIGKILL);
+	exit(0);
+}