vhost: comment unwanted callback

add comment for potential unwanted callback on listenfds

Signed-off-by: Huawei Xie <huawei.xie@intel.com>

diff --git a/lib/librte_vhost/vhost_user/fd_man.c b/lib/librte_vhost/vhost_user/fd_man.c
index bd30f8d..d68b270 100644 (file)
--- a/lib/librte_vhost/vhost_user/fd_man.c
+++ b/lib/librte_vhost/vhost_user/fd_man.c
@@ -242,6 +242,13 @@ fdset_event_dispatch(struct fdset *pfdset)
 
                pthread_mutex_unlock(&pfdset->fd_mutex);
 
+               /*
+                * When select is blocked, other threads might unregister
+                * listenfds from and register new listenfds into fdset.
+                * When select returns, the entries for listenfds in the fdset
+                * might have been updated. It is ok if there is unwanted call
+                * for new listenfds.
+                */
                ret = select(maxfds + 1, &rfds, &wfds, NULL, &tv);
                if (ret <= 0)
                        continue;