[ovs-dev] [PATCH] windows: Crash when the handle communication device cannot be found

[Alin Serdean]

When trying to uninstall/disable the OVS extension the driver will
fail to unload properly(require reboot)/hang until ovs-vswitchd is closed.

The root cause of this behavior is because the handles from ovs-vswitchd
to the kernel communication devices are still opened although the
actual device was removed from the kernel.

Trying to close the handles will also fail because they do not exist.

The remaining option is to cause a crash and rely on the service manager
to restart ovs-vswitchd.

Reported-at: https://github.com/openvswitch/ovs-issues/issues/27
Reported-by: Alin Gabriel Serdean <aserdean at cloudbasesolutions.com>
Signed-off-by: Alin Gabriel Serdean <aserdean at cloudbasesolutions.com>
---
 lib/netlink-socket.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c
index e45914c..4f56c60 100644
--- a/lib/netlink-socket.c
+++ b/lib/netlink-socket.c
@@ -60,6 +60,20 @@ static void log_nlmsg(const char *function, int error,
 #ifdef _WIN32
 static int get_sock_pid_from_kernel(struct nl_sock *sock);
 static int set_sock_property(struct nl_sock *sock);
+
+/* In the case DeviceIoControl failed and GetLastError returns with
+ * ERROR_NOT_FOUND means we lost communication with the kernel device.
+ * CloseHandle will fail because the handle in 'theory' does not exist.
+ * The only remaining option is to crash and allow the service to be restarted
+ * via service manager.  This is the only way to close the handle from both
+ * userspace and kernel. */
+void
+lost_communication(DWORD last_err)
+{
+    if (last_err == ERROR_NOT_FOUND) {
+        ovs_fatal(0, "lost communication with the kernel device");
+    }
+}
 #endif
 
 /* Netlink sockets. */
@@ -278,6 +292,7 @@ get_sock_pid_from_kernel(struct nl_sock *sock)
     if (!DeviceIoControl(sock->handle, OVS_IOCTL_GET_PID,
                          NULL, 0, &pid, sizeof(pid),
                          &bytes, NULL)) {
+        lost_communication(GetLastError());
         retval = EINVAL;
     } else {
         if (bytes < sizeof(pid)) {
@@ -535,11 +550,12 @@ nl_sock_send__(struct nl_sock *sock, const struct ofpbuf *msg,
         if (!DeviceIoControl(sock->handle, OVS_IOCTL_WRITE,
                              msg->data, msg->size, NULL, 0,
                              &bytes, NULL)) {
+            lost_communication(GetLastError());
             retval = -1;
             /* XXX: Map to a more appropriate error based on GetLastError(). */
             errno = EINVAL;
             VLOG_DBG_RL(&rl, "fatal driver failure in write: %s",
-                ovs_lasterror_to_string());
+                        ovs_lasterror_to_string());
         } else {
             retval = msg->size;
         }
@@ -629,6 +645,7 @@ nl_sock_recv__(struct nl_sock *sock, struct ofpbuf *buf, bool wait)
         DWORD bytes;
         if (!DeviceIoControl(sock->handle, sock->read_ioctl,
                              NULL, 0, tail, sizeof tail, &bytes, NULL)) {
+            lost_communication(GetLastError());
             VLOG_DBG_RL(&rl, "fatal driver failure in transact: %s",
                         ovs_lasterror_to_string());
             retval = -1;
@@ -879,6 +896,7 @@ nl_sock_transact_multiple__(struct nl_sock *sock,
             }
         } else if (!ret) {
             /* XXX: Map to a more appropriate error. */
+            lost_communication(GetLastError());
             error = EINVAL;
             VLOG_DBG_RL(&rl, "fatal driver failure: %s",
                 ovs_lasterror_to_string());
@@ -1275,6 +1293,7 @@ pend_io_request(struct nl_sock *sock)
         error = GetLastError();
         /* Check if the I/O got pended */
         if (error != ERROR_IO_INCOMPLETE && error != ERROR_IO_PENDING) {
+            lost_communication(error);
             VLOG_ERR("nl_sock_wait failed - %s\n", ovs_format_message(error));
             retval = EINVAL;
         }
-- 
2.10.2.windows.1