From 77fbe6944fd5bd29687162e2d0241646568a028f Mon Sep 17 00:00:00 2001
From: Alan Somers <asomers@FreeBSD.org>
Date: Wed, 15 May 2019 20:01:41 +0000
Subject: [PATCH] fusefs: fix more intermittency in the dev_fuse_poll tests

When using poll, kevent, or select there was a race window during which it
would be impossible to shut down the daemon.  The problem was that poll,
kevent, and select don't return when the file descriptor gets closed (or
maybe it was that the file descriptor got closed before those syscalls were
entered?).  The solution is to impose a timeout on those syscalls, and check
m_quit after they time out.

Sponsored by:	The FreeBSD Foundation
---
 tests/sys/fs/fusefs/mockfs.cc | 48 ++++++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 17 deletions(-)

diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc
index 053fff399e59..8a69a84711c2 100644
--- a/tests/sys/fs/fusefs/mockfs.cc
+++ b/tests/sys/fs/fusefs/mockfs.cc
@@ -500,23 +500,31 @@ void MockFS::process_default(const mockfs_buf_in *in,
 
 void MockFS::read_request(mockfs_buf_in *in) {
 	ssize_t res;
-	int nready;
+	int nready = 0;
 	fd_set readfds;
 	pollfd fds[1];
 	struct kevent changes[1];
 	struct kevent events[1];
-	int nfds;
+	struct timespec timeout_ts;
+	struct timeval timeout_tv;
+	const int timeout_ms = 999;
+	int timeout_int, nfds;
 
 	switch (m_pm) {
 	case BLOCKING:
 		break;
 	case KQ:
-		EV_SET(&changes[0], m_fuse_fd, EVFILT_READ, EV_ADD, 0, 0, 0);
-		nready = kevent(m_kq, &changes[0], 1, &events[0], 1, NULL);
-		if (m_quit)
-			return;
+		timeout_ts.tv_sec = 0;
+		timeout_ts.tv_nsec = timeout_ms * 1'000'000;
+		while (nready == 0) {
+			EV_SET(&changes[0], m_fuse_fd, EVFILT_READ, EV_ADD, 0,
+				0, 0);
+			nready = kevent(m_kq, &changes[0], 1, &events[0], 1,
+				&timeout_ts);
+			if (m_quit)
+				return;
+		}
 		ASSERT_LE(0, nready) << strerror(errno);
-		ASSERT_EQ(1, nready) << "NULL timeout expired?";
 		ASSERT_EQ(events[0].ident, (uintptr_t)m_fuse_fd);
 		if (events[0].flags & EV_ERROR)
 			FAIL() << strerror(events[0].data);
@@ -525,24 +533,30 @@ void MockFS::read_request(mockfs_buf_in *in) {
 		m_nready = events[0].data;
 		break;
 	case POLL:
+		timeout_int = timeout_ms;
 		fds[0].fd = m_fuse_fd;
 		fds[0].events = POLLIN;
-		nready = poll(fds, 1, INFTIM);
-		if (m_quit)
-			return;
+		while (nready == 0) {
+			nready = poll(fds, 1, timeout_int);
+			if (m_quit)
+				return;
+		}
 		ASSERT_LE(0, nready) << strerror(errno);
-		ASSERT_EQ(1, nready) << "NULL timeout expired?";
 		ASSERT_TRUE(fds[0].revents & POLLIN);
 		break;
 	case SELECT:
-		FD_ZERO(&readfds);
-		FD_SET(m_fuse_fd, &readfds);
+		timeout_tv.tv_sec = 0;
+		timeout_tv.tv_usec = timeout_ms * 1'000;
 		nfds = m_fuse_fd + 1;
-		nready = select(nfds, &readfds, NULL, NULL, NULL);
-		if (m_quit)
-			return;
+		while (nready == 0) {
+			FD_ZERO(&readfds);
+			FD_SET(m_fuse_fd, &readfds);
+			nready = select(nfds, &readfds, NULL, NULL,
+				&timeout_tv);
+			if (m_quit)
+				return;
+		}
 		ASSERT_LE(0, nready) << strerror(errno);
-		ASSERT_EQ(1, nready) << "NULL timeout expired?";
 		ASSERT_TRUE(FD_ISSET(m_fuse_fd, &readfds));
 		break;
 	default: