net/dcb: Add an optional max rate attribute

Although not specified in 8021Qaz spec, it could be useful to enable drivers
whose HW supports setting a rate limit for an ETS TC. This patch adds this
optional attribute to DCB netlink. To use it, drivers should implement and
register the callbacks ieee_setmaxrate and ieee_getmaxrate. The units are 64
bits long and specified in Kbps to enable usage over both slow and very fast
networks.

Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index 36f37af..8dfa1da 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -178,6 +178,7 @@
 	[DCB_ATTR_IEEE_ETS]	    = {.len = sizeof(struct ieee_ets)},
 	[DCB_ATTR_IEEE_PFC]	    = {.len = sizeof(struct ieee_pfc)},
 	[DCB_ATTR_IEEE_APP_TABLE]   = {.type = NLA_NESTED},
+	[DCB_ATTR_IEEE_MAXRATE]   = {.len = sizeof(struct ieee_maxrate)},
 };
 
 static const struct nla_policy dcbnl_ieee_app[DCB_ATTR_IEEE_APP_MAX + 1] = {
@@ -1246,6 +1247,17 @@
 			goto nla_put_failure;
 	}
 
+	if (ops->ieee_getmaxrate) {
+		struct ieee_maxrate maxrate;
+		err = ops->ieee_getmaxrate(netdev, &maxrate);
+		if (!err) {
+			err = nla_put(skb, DCB_ATTR_IEEE_MAXRATE,
+				      sizeof(maxrate), &maxrate);
+			if (err)
+				goto nla_put_failure;
+		}
+	}
+
 	if (ops->ieee_getpfc) {
 		struct ieee_pfc pfc;
 		err = ops->ieee_getpfc(netdev, &pfc);
@@ -1601,6 +1613,14 @@
 			goto err;
 	}
 
+	if (ieee[DCB_ATTR_IEEE_MAXRATE] && ops->ieee_setmaxrate) {
+		struct ieee_maxrate *maxrate =
+			nla_data(ieee[DCB_ATTR_IEEE_MAXRATE]);
+		err = ops->ieee_setmaxrate(netdev, maxrate);
+		if (err)
+			goto err;
+	}
+
 	if (ieee[DCB_ATTR_IEEE_PFC] && ops->ieee_setpfc) {
 		struct ieee_pfc *pfc = nla_data(ieee[DCB_ATTR_IEEE_PFC]);
 		err = ops->ieee_setpfc(netdev, pfc);