Merge branch 'net-sched-Make-qdisc-offload-uapi-uniform'

Yuval Mintz says:

====================
net: sched: Make qdisc offload uapi uniform

Several qdiscs can already be offloaded to hardware, but there's an
inconsistecy in regard to the uapi through which they indicate such
an offload is taking place - indication is passed to the user via
TCA_OPTIONS where each qdisc retains private logic for setting it.

The recent addition of offloading to RED in
602f3baf2218 ("net_sch: red: Add offload ability to RED qdisc") caused
the addition of yet another uapi field for this purpose -
TC_RED_OFFLOADED.

For clarity and prevention of bloat in the uapi we want to eliminate
said added uapi, replacing it with a common mechanism that can be used
to reflect offload status of the various qdiscs.

The first patch introduces TCA_HW_OFFLOAD as the generic message meant
for this purpose. The second changes the current RED implementation into
setting the internal bits necessary for passing it, and the third removes
TC_RED_OFFLOADED as its no longer needed.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 19 insertions, 17 deletions

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 65d0d25f2648..83a3e47d5845 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -71,6 +71,7 @@ struct Qdisc {
                                       * qdisc_tree_decrease_qlen() should stop.
                                       */
 #define TCQ_F_INVISIBLE         0x80 /* invisible by default in dump */
+#define TCQ_F_OFFLOADED         0x200 /* qdisc is offloaded to HW */
         u32                     limit;
         const struct Qdisc_ops  *ops;
         struct qdisc_size_table __rcu *stab;
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index af3cc2f4e1ad..37b5096ae97b 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -256,7 +256,6 @@ struct tc_red_qopt {
 #define TC_RED_ECN              1
 #define TC_RED_HARDDROP         2
 #define TC_RED_ADAPTATIVE       4
-#define TC_RED_OFFLOADED        8
 };
 
 struct tc_red_xstats {
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index d8b5f80c2ea6..843e29aa3cac 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -557,6 +557,7 @@ enum {
         TCA_PAD,
         TCA_DUMP_INVISIBLE,
         TCA_CHAIN,
+        TCA_HW_OFFLOAD,
         __TCA_MAX
 };
 
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index b6c4f536876b..0f1eab99ff4e 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -795,6 +795,8 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
         tcm->tcm_info = refcount_read(&q->refcnt);
         if (nla_put_string(skb, TCA_KIND, q->ops->id))
                 goto nla_put_failure;
+        if (nla_put_u8(skb, TCA_HW_OFFLOAD, !!(q->flags & TCQ_F_OFFLOADED)))
+                goto nla_put_failure;
         if (q->ops->dump && q->ops->dump(q, skb) < 0)
                 goto nla_put_failure;
         qlen = q->q.qlen;
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index 9d874e60e032..f0747eb87dc4 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -157,6 +157,7 @@ static int red_offload(struct Qdisc *sch, bool enable)
                 .handle = sch->handle,
                 .parent = sch->parent,
         };
+        int err;
 
         if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
                 return -EOPNOTSUPP;
@@ -171,7 +172,14 @@ static int red_offload(struct Qdisc *sch, bool enable)
                 opt.command = TC_RED_DESTROY;
         }
 
-        return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt);
+        err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt);
+
+        if (!err && enable)
+                sch->flags |= TCQ_F_OFFLOADED;
+        else
+                sch->flags &= ~TCQ_F_OFFLOADED;
+
+        return err;
 }
 
 static void red_destroy(struct Qdisc *sch)
@@ -274,7 +282,7 @@ static int red_init(struct Qdisc *sch, struct nlattr *opt)
         return red_change(sch, opt);
 }
 
-static int red_dump_offload(struct Qdisc *sch, struct tc_red_qopt *opt)
+static int red_dump_offload_stats(struct Qdisc *sch, struct tc_red_qopt *opt)
 {
         struct net_device *dev = qdisc_dev(sch);
         struct tc_red_qopt_offload hw_stats = {
@@ -286,21 +294,12 @@ static int red_dump_offload(struct Qdisc *sch, struct tc_red_qopt *opt)
                         .stats.qstats = &sch->qstats,
                 },
         };
-        int err;
 
-        opt->flags &= ~TC_RED_OFFLOADED;
-        if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
-                return 0;
-
-        err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
-                                            &hw_stats);
-        if (err == -EOPNOTSUPP)
+        if (!(sch->flags & TCQ_F_OFFLOADED))
                 return 0;
 
-        if (!err)
-                opt->flags |= TC_RED_OFFLOADED;
-
-        return err;
+        return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
+                                             &hw_stats);
 }
 
 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
@@ -319,7 +318,7 @@ static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
         int err;
 
         sch->qstats.backlog = q->qdisc->qstats.backlog;
-        err = red_dump_offload(sch, &opt);
+        err = red_dump_offload_stats(sch, &opt);
         if (err)
                 goto nla_put_failure;
 
@@ -347,7 +346,7 @@ static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
                 .marked = q->stats.prob_mark + q->stats.forced_mark,
         };
 
-        if (tc_can_offload(dev) &&  dev->netdev_ops->ndo_setup_tc) {
+        if (sch->flags & TCQ_F_OFFLOADED) {
                 struct red_stats hw_stats = {0};
                 struct tc_red_qopt_offload hw_stats_request = {
                         .command = TC_RED_XSTATS,