nbd: Close socket on negotiation failure.

Otherwise, the nbd client may hang waiting for the server response.
Signed-off-by: NHani Benhabiles <hani@linux.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>
(cherry picked from commit 36af5994)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

blockdev-nbd.c

@@ -27,8 +27,8 @@ static void nbd_accept(void *opaque)
     socklen_t addr_len = sizeof(addr);
 
     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
-    if (fd >= 0) {
-        nbd_client_new(NULL, fd, nbd_client_put);
+    if (fd >= 0 && !nbd_client_new(NULL, fd, nbd_client_put)) {
+        close(fd);
     }
 }
 

qemu-nbd.c

@@ -369,8 +369,10 @@ static void nbd_accept(void *opaque)
         return;
     }
 
-    if (fd >= 0 && nbd_client_new(exp, fd, nbd_client_closed)) {
+    if (nbd_client_new(exp, fd, nbd_client_closed)) {
         nb_fds++;
+    } else {
+        close(fd);
     }
 }