[RFC net-next 4/4] net: sched: cls_matchall: implement offload tcf_proto_op

[Jakub Kicinski]

From: John Hurley <john.hur...@netronome.com>

Add the offload tcf_proto_op in matchall to generate an offload message
for each filter in the given tcf_proto. Call the specified callback with
this new offload message. The function only returns an error if the
callback rejects adding a 'hardware only' rule.

Ensure matchall flags correctly report if the rule is in hw by keeping a
reference counter for the number of instances of the rule offloaded. Only
update the flag when this counter changes from or to 0.

Signed-off-by: John Hurley <john.hur...@netronome.com>
---
 net/sched/cls_matchall.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c
index 2ba721a590a7..a3497bc4ee24 100644
--- a/net/sched/cls_matchall.c
+++ b/net/sched/cls_matchall.c
@@ -21,6 +21,7 @@ struct cls_mall_head {
        struct tcf_result res;
        u32 handle;
        u32 flags;
+       u32 in_hw_count;
        union {
                struct work_struct work;
                struct rcu_head rcu;
@@ -106,6 +107,7 @@ static int mall_replace_hw_filter(struct tcf_proto *tp,
                mall_destroy_hw_filter(tp, head, cookie, NULL);
                return err;
        } else if (err > 0) {
+               head->in_hw_count = err;
                tcf_block_offload_inc(block, &head->flags);
        }
 
@@ -246,6 +248,43 @@ static void mall_walk(struct tcf_proto *tp, struct 
tcf_walker *arg)
        arg->count++;
 }
 
+static int mall_offload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
+                       void *cb_priv, struct netlink_ext_ack *extack)
+{
+       struct cls_mall_head *head = rtnl_dereference(tp->root);
+       struct tc_cls_matchall_offload cls_mall = {};
+       struct tcf_block *block = tp->chain->block;
+       int err;
+
+       if (tc_skip_hw(head->flags))
+               return 0;
+
+       tc_cls_common_offload_init(&cls_mall.common, tp, head->flags, extack);
+       cls_mall.command = add ?
+               TC_CLSMATCHALL_REPLACE : TC_CLSMATCHALL_DESTROY;
+       cls_mall.exts = &head->exts;
+       cls_mall.cookie = (unsigned long)head;
+
+       err = cb(TC_SETUP_CLSMATCHALL, &cls_mall, cb_priv);
+       if (err) {
+               if (add && tc_skip_sw(head->flags))
+                       return err;
+               return 0;
+       }
+
+       if (add) {
+               if (!head->in_hw_count)
+                       tcf_block_offload_inc(block, &head->flags);
+               head->in_hw_count++;
+       } else {
+               head->in_hw_count--;
+               if (!head->in_hw_count)
+                       tcf_block_offload_dec(block, &head->flags);
+       }
+
+       return 0;
+}
+
 static int mall_dump(struct net *net, struct tcf_proto *tp, void *fh,
                     struct sk_buff *skb, struct tcmsg *t)
 {
@@ -300,6 +339,7 @@ static struct tcf_proto_ops cls_mall_ops __read_mostly = {
        .change         = mall_change,
        .delete         = mall_delete,
        .walk           = mall_walk,
+       .offload        = mall_offload,
        .dump           = mall_dump,
        .bind_class     = mall_bind_class,
        .owner          = THIS_MODULE,
-- 
2.17.0