dpif-linux: Close channel Netlink sockets when a port number gets rec…

…ycled.

When ovs-vswitchd deletes a port with dpif_linux_port_del(), that function
uses del_channel() to delete the corresponding channel, including closing
its Netlink socket fd.  However, if the vport gets removed by some other
process (e.g. "ip link delete" for veths) then this function never gets
called and thus the channel never gets deleted.

This commit partially fixes the problem.  Now, if a port number gets
reused, add_channel() closes the old Netlink socket assigned to that port
before it installs the new one.

Bug #16784.
Reported-by: Paul Ingram <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>

lib/dpif-linux.c

@@ -337,6 +337,7 @@ add_channel(struct dpif_linux *dpif, uint32_t port_no, struct nl_sock *sock)
         return errno;
     }
 
+    nl_sock_destroy(dpif->channels[port_no].sock);
     dpif->channels[port_no].sock = sock;
     dpif->channels[port_no].last_poll = LLONG_MIN;