Add a (failing) test for a deadlock with fifos and threads.

The ``sleep until we have a writer'' behaviour of an open() on a fifo
does so with the file descriptor table locked, so if we are waiting for
another thread to be our writer we will hang forever.

Found this using zotero and firefox.

ok fgsch@

2 files changed, 88 insertions, 0 deletions

diff --git a/regress/lib/libpthread/blocked_fifo/Makefile b/regress/lib/libpthread/blocked_fifo/Makefile
new file mode 100644
index 00000000000..acffb22842c
--- /dev/null
+++ b/regress/lib/libpthread/blocked_fifo/Makefile
@@ -0,0 +1,5 @@
+# $OpenBSD: Makefile,v 1.1 2012/03/19 17:41:57 oga Exp $
+
+PROG=	blocked_fifo
+
+.include <bsd.regress.mk>
diff --git a/regress/lib/libpthread/blocked_fifo/blocked_fifo.c b/regress/lib/libpthread/blocked_fifo/blocked_fifo.c
new file mode 100644
index 00000000000..c5dc63bc45d
--- /dev/null
+++ b/regress/lib/libpthread/blocked_fifo/blocked_fifo.c
@@ -0,0 +1,83 @@
+/*	$OpenBSD: blocked_fifo.c,v 1.1 2012/03/19 17:41:57 oga Exp $	*/
+/*
+ * Copyright (c) 2012 Owain G. Ainsworth <oga@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Test fifo opening blocking the file descriptor table and thus all other
+ * opens in the process.
+ * Symptoms are that the main thread will sleep on fifor (in the fifo open) and
+ * the deadlocker on fdlock (in open of any other file).
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <pthread.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "test.h"
+
+#define FIFO	"/tmp/pthread.fifo"
+#define FILE	"/etc/services"	/* just any file to deadlock on */
+
+static void *
+deadlock_detector(void *arg)
+{
+	sleep(10);
+	unlink(FIFO);
+	PANIC("deadlock detected");
+}
+
+static void *
+fifo_deadlocker(void *arg)
+{
+	int	fd;
+
+	/* let other fifo open start */
+	sleep(3);
+
+	/* open a random temporary file, if we don't deadlock this'll succeed */
+	CHECKe(fd = open(FILE, O_RDONLY));
+	CHECKe(close(fd));
+
+	/* open fifo to unblock other thread */
+	CHECKe(fd = open(FIFO, O_WRONLY));
+
+	return ((caddr_t)NULL + errno);
+}
+
+int
+main(int argc, char *argv[])
+{
+	pthread_t	 deadlock_thread, deadlock_finder;
+	int		 fd;
+
+	CHECKe(mkfifo(FIFO, S_IRUSR | S_IWUSR));
+
+	CHECKr(pthread_create(&deadlock_thread, NULL,
+	    fifo_deadlocker, NULL));
+	CHECKr(pthread_create(&deadlock_finder, NULL,
+	    deadlock_detector, NULL));
+
+	/* Open fifo (this will sleep until we have readers */
+	CHECKe(fd = open(FIFO, O_RDONLY));
+
+	CHECKr(pthread_join(deadlock_thread, NULL));
+
+	unlink(FIFO);
+
+	SUCCEED;
+}