net: sched: cls_bpf: implement offload tcf_proto_op

Add the offload tcf_proto_op in cls_bpf to generate an offload message for
each bpf prog 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' prog.

A prog contains a flag to indicate if it is in hardware or not. To
ensure the offload function properly maintains this flag, keep a reference
counter for the number of instances of the prog that are in hardware. Only
update the flag when this counter changes from or to 0.
Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_bpf.c

@@ -43,6 +43,7 @@ struct cls_bpf_prog {
 	struct tcf_result res;
 	bool exts_integrated;
 	u32 gen_flags;
+	unsigned int in_hw_count;
 	struct tcf_exts exts;
 	u32 handle;
 	u16 bpf_num_ops;
@@ -174,6 +175,7 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 			cls_bpf_offload_cmd(tp, oldprog, prog, extack);
 			return err;
 		} else if (err > 0) {
+			prog->in_hw_count = err;
 			tcf_block_offload_inc(block, &prog->gen_flags);
 		}
 	}
@@ -652,6 +654,42 @@ static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 	}
 }
 
+static int cls_bpf_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
+			     void *cb_priv, struct netlink_ext_ack *extack)
+{
+	struct cls_bpf_head *head = rtnl_dereference(tp->root);
+	struct tcf_block *block = tp->chain->block;
+	struct tc_cls_bpf_offload cls_bpf = {};
+	struct cls_bpf_prog *prog;
+	int err;
+
+	list_for_each_entry(prog, &head->plist, link) {
+		if (tc_skip_hw(prog->gen_flags))
+			continue;
+
+		tc_cls_common_offload_init(&cls_bpf.common, tp, prog->gen_flags,
+					   extack);
+		cls_bpf.command = TC_CLSBPF_OFFLOAD;
+		cls_bpf.exts = &prog->exts;
+		cls_bpf.prog = add ? prog->filter : NULL;
+		cls_bpf.oldprog = add ? NULL : prog->filter;
+		cls_bpf.name = prog->bpf_name;
+		cls_bpf.exts_integrated = prog->exts_integrated;
+
+		err = cb(TC_SETUP_CLSBPF, &cls_bpf, cb_priv);
+		if (err) {
+			if (add && tc_skip_sw(prog->gen_flags))
+				return err;
+			continue;
+		}
+
+		tc_cls_offload_cnt_update(block, &prog->in_hw_count,
+					  &prog->gen_flags, add);
+	}
+
+	return 0;
+}
+
 static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
 	.kind		=	"bpf",
 	.owner		=	THIS_MODULE,
@@ -662,6 +700,7 @@ static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
 	.change		=	cls_bpf_change,
 	.delete		=	cls_bpf_delete,
 	.walk		=	cls_bpf_walk,
+	.reoffload	=	cls_bpf_reoffload,
 	.dump		=	cls_bpf_dump,
 	.bind_class	=	cls_bpf_bind_class,
 };