tc: Add TCA_KIND flower to delete and get operation to avoid rtnl_lock().

A long long time ago, an effort was made to make tc flower
rtnl_lock() free. However, on the OVS part we forgot to add
the TCA_KIND "flower" attribute, which tell the kernel to skip
the lock. This patch corrects this by adding the attribute for
the delete and get operations.

The kernel code calls tcf_proto_is_unlocked() to determine the
rtnl_lock() is needed for the specific tc protocol. It does this
in the tc_new_tfilter(), tc_del_tfilter(), and in tc_get_tfilter().

If the name is not set, tcf_proto_is_unlocked() will always return
false. If set, the specific protocol is queried for unlocked support.

Fixes: f98e418fbdb6 ("tc: Add tc flower functions")
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

4 files changed, 22 insertions, 13 deletions

diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index f6d7a1b97..65bdd51db 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -2735,7 +2735,7 @@ tc_del_matchall_policer(struct netdev *netdev)
     }
 
     id = tc_make_tcf_id(ifindex, block_id, prio, TC_INGRESS);
-    err = tc_del_filter(&id);
+    err = tc_del_filter(&id, "matchall");
     if (err) {
         return err;
     }
diff --git a/lib/netdev-offload-tc.c b/lib/netdev-offload-tc.c
index 15d1c36aa..6e1bbaa28 100644
--- a/lib/netdev-offload-tc.c
+++ b/lib/netdev-offload-tc.c
@@ -239,7 +239,7 @@ del_filter_and_ufid_mapping(struct tcf_id *id, const ovs_u128 *ufid)
 {
     int err;
 
-    err = tc_del_filter(id);
+    err = tc_del_flower_filter(id);
     if (!err) {
         del_ufid_tc_mapping(ufid);
     }
@@ -461,7 +461,7 @@ delete_chains_from_netdev(struct netdev *netdev, struct tcf_id *id)
          */
         HMAP_FOR_EACH_POP (chain_node, node, &map) {
             id->chain = chain_node->chain;
-            tc_del_filter(id);
+            tc_del_flower_filter(id);
             free(chain_node);
         }
     }
@@ -482,7 +482,7 @@ netdev_tc_flow_flush(struct netdev *netdev)
             continue;
         }
 
-        err = tc_del_filter(&data->id);
+        err = tc_del_flower_filter(&data->id);
         if (!err) {
             del_ufid_tc_mapping_unlocked(&data->ufid);
         }
@@ -2499,13 +2499,13 @@ probe_multi_mask_per_prio(int ifindex)
 
     id2 = tc_make_tcf_id(ifindex, block_id, prio, TC_INGRESS);
     error = tc_replace_flower(&id2, &flower);
-    tc_del_filter(&id1);
+    tc_del_flower_filter(&id1);
 
     if (error) {
         goto out;
     }
 
-    tc_del_filter(&id2);
+    tc_del_flower_filter(&id2);
 
     multi_mask_per_prio = true;
     VLOG_INFO("probe tc: multiple masks on single tc prio is supported.");
@@ -2557,7 +2557,7 @@ probe_ct_state_support(int ifindex)
         goto out_del;
     }
 
-    tc_del_filter(&id);
+    tc_del_flower_filter(&id);
     ct_state_support = OVS_CS_F_NEW |
                        OVS_CS_F_ESTABLISHED |
                        OVS_CS_F_TRACKED |
@@ -2571,7 +2571,7 @@ probe_ct_state_support(int ifindex)
         goto out_del;
     }
 
-    tc_del_filter(&id);
+    tc_del_flower_filter(&id);
 
     /* Test for ct_state INVALID support */
     memset(&flower, 0, sizeof flower);
@@ -2582,7 +2582,7 @@ probe_ct_state_support(int ifindex)
         goto out;
     }
 
-    tc_del_filter(&id);
+    tc_del_flower_filter(&id);
     ct_state_support |= OVS_CS_F_INVALID;
 
     /* Test for ct_state REPLY support */
@@ -2598,7 +2598,7 @@ probe_ct_state_support(int ifindex)
     ct_state_support |= OVS_CS_F_REPLY_DIR;
 
 out_del:
-    tc_del_filter(&id);
+    tc_del_flower_filter(&id);
 out:
     tc_add_del_qdisc(ifindex, false, 0, TC_INGRESS);
     VLOG_INFO("probe tc: supported ovs ct_state bits: 0x%x", ct_state_support);
@@ -2751,7 +2751,7 @@ netdev_tc_init_flow_api(struct netdev *netdev)
 
     /* fallback here if delete chains fail */
     if (!get_chain_supported) {
-        tc_del_filter(&id);
+        tc_del_flower_filter(&id);
     }
 
     /* make sure there is no ingress/egress qdisc */
diff --git a/lib/tc.c b/lib/tc.c
index 447ab376e..1fb2b4a92 100644
--- a/lib/tc.c
+++ b/lib/tc.c
@@ -2337,15 +2337,22 @@ parse_netlink_to_tc_policer(struct ofpbuf *reply, uint32_t police_idx[])
 }
 
 int
-tc_del_filter(struct tcf_id *id)
+tc_del_filter(struct tcf_id *id, const char *kind)
 {
     struct ofpbuf request;
 
     request_from_tcf_id(id, 0, RTM_DELTFILTER, NLM_F_ACK, &request);
+    nl_msg_put_string(&request, TCA_KIND, kind);
     return tc_transact(&request, NULL);
 }
 
 int
+tc_del_flower_filter(struct tcf_id *id)
+{
+    return tc_del_filter(id, "flower");
+}
+
+int
 tc_get_flower(struct tcf_id *id, struct tc_flower *flower)
 {
     struct ofpbuf request;
@@ -2353,6 +2360,7 @@ tc_get_flower(struct tcf_id *id, struct tc_flower *flower)
     int error;
 
     request_from_tcf_id(id, 0, RTM_GETTFILTER, NLM_F_ECHO, &request);
+    nl_msg_put_string(&request, TCA_KIND, "flower");
     error = tc_transact(&request, &reply);
     if (error) {
         return error;
diff --git a/lib/tc.h b/lib/tc.h
index a828fd3e3..ea4ce806b 100644
--- a/lib/tc.h
+++ b/lib/tc.h
@@ -384,7 +384,8 @@ struct tc_flower {
 };
 
 int tc_replace_flower(struct tcf_id *id, struct tc_flower *flower);
-int tc_del_filter(struct tcf_id *id);
+int tc_del_filter(struct tcf_id *id, const char *kind);
+int tc_del_flower_filter(struct tcf_id *id);
 int tc_get_flower(struct tcf_id *id, struct tc_flower *flower);
 int tc_dump_flower_start(struct tcf_id *id, struct nl_dump *dump, bool terse);
 int tc_dump_tc_chain_start(struct tcf_id *id, struct nl_dump *dump);