migrate_fd_close: delete associated io-handler before closing the fd

It may happen that the io-handler is still registered. That causes select() to return with EBADF, not calling handlers for other fds. The io-handler would be registered when (on the source) the whole state was written but not yet flushed. For example when using QEMUFileBuffered, (tcp-migration) there may be data left in a buffer waiting to be transferred. In such a case buffered_close() calls buffered_flush() which calls migrate_fd_put_buffer, which may, upon EAGAIN, register migrate_fd_put_notify as a handler. Signed-off-by: Uri Lublin <uril@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

migrate_fd_close: delete associated io-handler before closing the fd
It may happen that the io-handler is still registered. That causes select() to return with EBADF, not calling handlers for other fds. The io-handler would be registered when (on the source) the whole state was written but not yet flushed. For example when using QEMUFileBuffered, (tcp-migration) there may be data left in a buffer waiting to be transferred. In such a case buffered_close() calls buffered_flush() which calls migrate_fd_put_buffer, which may, upon EAGAIN, register migrate_fd_put_notify as a handler. Signed-off-by: Uri Lublin <uril@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Uri Lublin · Anthony Liguori
1 parent 8a67ec4d
Showing 1 changed file with 2 additions and 0 deletions
migration.c
@@ -301,5 +301,7 @@ void migrate_fd_wait_for_unfreeze(void *opaque)
 int migrate_fd_close(void *opaque)
 {
     FdMigrationState *s = opaque;
+
+    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
     return s->close(s);
 }