Prevent clovisor from unable to create qdisc / filter from previous

instance dying abnormally (qdisc deletion is part of exit callback for
pod under monitoring, but if clovisor exits abnormally, qdisc would not
be deleted, which cause the restarted new clovisor pod unable to load
BPF code to the pods under monitoring)

Change-Id: I5620f34e7f05805e203d1cfda9a8f7a1d42fd4f5
Signed-off-by: Stephen Wong <stephen.kf.wong@gmail.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/clover/clovisor/libclovisor/clovisor_bcc.go b/clover/clovisor/libclovisor/clovisor_bcc.go
index e2d9cd8..ab5bc33 100644
--- a/clover/clovisor/libclovisor/clovisor_bcc.go
+++ b/clover/clovisor/libclovisor/clovisor_bcc.go
@@ -509,6 +509,22 @@ func ClovisorNewPodInit(k8s_client *ClovisorK8s,
 
     session_table := bcc.NewTable(bpf_mod.TableId("sessions"), bpf_mod)
 
+    // check if qdisc clsact filter for this interface already exists
+    link, err := netlink.LinkByIndex(ifindex)
+    if err != nil {
+        fmt.Println(err)
+    } else {
+        qdiscs, err := netlink.QdiscList(link)
+        if err == nil {
+            for _, qdisc := range qdiscs {
+                if qdisc.Type() == "clsact" {
+                    netlink.QdiscDel(qdisc)
+                    break
+                }
+            }
+        }
+    }
+
     attrs := netlink.QdiscAttrs {
         LinkIndex: ifindex,
         Handle: netlink.MakeHandle(0xffff, 0),