util/aio-win32: Only select on what we are actually waiting for

Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Acked-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 9307b70e9876c4e9e3c4478524a32a23a3d5dd05.1499368180.git.alistair.francis@xilinx.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

util/aio-win32.c

@@ -71,6 +71,7 @@ void aio_set_fd_handler(AioContext *ctx,
         }
     } else {
         HANDLE event;
+        long bitmask = 0;
 
         if (node == NULL) {
             /* Alloc and insert if it's not already there */
@@ -95,10 +96,16 @@ void aio_set_fd_handler(AioContext *ctx,
         node->io_write = io_write;
         node->is_external = is_external;
 
+        if (io_read) {
+            bitmask |= FD_READ | FD_ACCEPT | FD_CLOSE;
+        }
+
+        if (io_write) {
+            bitmask |= FD_WRITE | FD_CONNECT;
+        }
+
         event = event_notifier_get_handle(&ctx->notifier);
-        WSAEventSelect(node->pfd.fd, event,
-                       FD_READ | FD_ACCEPT | FD_CLOSE |
-                       FD_CONNECT | FD_WRITE | FD_OOB);
+        WSAEventSelect(node->pfd.fd, event, bitmask);
     }
 
     qemu_lockcnt_unlock(&ctx->list_lock);