[RFC 04/12] net: cls_bpf: add support for marking filters as hardware-only

[Jakub Kicinski]

Add cls_bpf support for the TCA_CLS_FLAGS_SKIP_SW flag.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Reviewed-by: Dinan Gunawardena <dgunaward...@netronome.com>
Reviewed-by: Simon Horman <simon.hor...@netronome.com>
---
 net/sched/cls_bpf.c | 39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 9f1bc37dcbbc..1083910cebaf 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -28,7 +28,7 @@ MODULE_DESCRIPTION("TC BPF based classifier");
 
 #define CLS_BPF_NAME_LEN       256
 #define CLS_BPF_SUPPORTED_GEN_FLAGS            \
-       TCA_CLS_FLAGS_SKIP_HW
+       (TCA_CLS_FLAGS_SKIP_HW | TCA_CLS_FLAGS_SKIP_SW)
 
 struct cls_bpf_head {
        struct list_head plist;
@@ -98,7 +98,9 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct 
tcf_proto *tp,
 
                qdisc_skb_cb(skb)->tc_classid = prog->res.classid;
 
-               if (at_ingress) {
+               if (tc_skip_sw(prog->gen_flags)) {
+                       filter_res = 0;
+               } else if (at_ingress) {
                        /* It is safe to push/pull even if skb_shared() */
                        __skb_push(skb, skb->mac_len);
                        bpf_compute_data_end(skb);
@@ -166,32 +168,42 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, 
struct cls_bpf_prog *prog,
                                             tp->protocol, &offload);
 }
 
-static void cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
-                           struct cls_bpf_prog *oldprog)
+static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
+                          struct cls_bpf_prog *oldprog)
 {
        struct net_device *dev = tp->q->dev_queue->dev;
        struct cls_bpf_prog *obj = prog;
        enum tc_clsbpf_command cmd;
+       bool skip_sw;
+       int ret;
+
+       skip_sw = tc_skip_sw(prog->gen_flags) ||
+               (oldprog && tc_skip_sw(oldprog->gen_flags));
 
        if (oldprog && oldprog->offloaded) {
                if (tc_should_offload(dev, prog->gen_flags)) {
                        cmd = TC_CLSBPF_REPLACE;
-               } else {
+               } else if (!tc_skip_sw(prog->gen_flags)) {
                        obj = oldprog;
                        cmd = TC_CLSBPF_DESTROY;
+               } else {
+                       return -EINVAL;
                }
        } else {
                if (!tc_should_offload(dev, prog->gen_flags))
-                       return;
+                       return skip_sw ? -EINVAL : 0;;
                cmd = TC_CLSBPF_ADD;
        }
 
-       if (cls_bpf_offload_cmd(tp, obj, cmd))
-               return;
+       ret = cls_bpf_offload_cmd(tp, obj, cmd);
+       if (ret)
+               return skip_sw ? ret : 0;
 
        obj->offloaded = true;
        if (oldprog)
                oldprog->offloaded = false;
+
+       return 0;
 }
 
 static void cls_bpf_stop_offload(struct tcf_proto *tp,
@@ -406,8 +418,11 @@ static int cls_bpf_modify_existing(struct net *net, struct 
tcf_proto *tp,
 
                have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT;
        }
-       if (tb[TCA_BPF_GEN_TCA_FLAGS])
+       if (tb[TCA_BPF_GEN_TCA_FLAGS]) {
                gen_flags = nla_get_u32(tb[TCA_BPF_GEN_TCA_FLAGS]);
+               if (!tc_flags_valid(gen_flags))
+                       return -EINVAL;
+       }
 
        prog->exts_integrated = have_exts;
        prog->gen_flags = gen_flags & CLS_BPF_SUPPORTED_GEN_FLAGS;
@@ -493,7 +508,11 @@ static int cls_bpf_change(struct net *net, struct sk_buff 
*in_skb,
        if (ret < 0)
                goto errout;
 
-       cls_bpf_offload(tp, prog, oldprog);
+       ret = cls_bpf_offload(tp, prog, oldprog);
+       if (ret) {
+               cls_bpf_delete_prog(tp, prog);
+               return ret;
+       }
 
        if (oldprog) {
                list_replace_rcu(&oldprog->link, &prog->link);
-- 
1.9.1