[net-next v3 1/6] net: dcb: add new pcp selector to app object

[Daniel Machon]

Add new PCP selector for the 8021Qaz APP managed object.

As the PCP selector is not part of the 8021Qaz standard, a new non-std
extension attribute DCB_ATTR_DCB_APP has been introduced. Also two
helper functions to translate between selector and app attribute type
has been added. The new selector has been given a value of 255, to
minimize the risk of future overlap of std- and non-std attributes.

The new DCB_ATTR_DCB_APP is sent alongside the ieee std attribute in the
app table. This means that the dcb_app struct can now both contain std-
and non-std app attributes. Currently there is no overlap between the
selector values of the two attributes.

The purpose of adding the PCP selector, is to be able to offload
PCP-based queue classification to the 8021Q Priority Code Point table,
see 6.9.3 of IEEE Std 802.1Q-2018.

PCP and DEI is encoded in the protocol field as 8*dei+pcp, so that a
mapping of PCP 2 and DEI 1 to priority 3 is encoded as {255, 10, 3}.

Signed-off-by: Daniel Machon <daniel.machon@xxxxxxxxxxxxx>
---
 include/uapi/linux/dcbnl.h |  6 ++++++
 net/dcb/dcbnl.c            | 36 ++++++++++++++++++++++++++++++++----
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/dcbnl.h b/include/uapi/linux/dcbnl.h
index a791a94013a6..dc7ef96207ca 100644
--- a/include/uapi/linux/dcbnl.h
+++ b/include/uapi/linux/dcbnl.h
@@ -218,6 +218,9 @@ struct cee_pfc {
 #define IEEE_8021QAZ_APP_SEL_ANY	4
 #define IEEE_8021QAZ_APP_SEL_DSCP       5
 
+/* Non-std selector values */
+#define DCB_APP_SEL_PCP 255
+
 /* This structure contains the IEEE 802.1Qaz APP managed object. This
  * object is also used for the CEE std as well.
  *
@@ -247,6 +250,8 @@ struct dcb_app {
 	__u16	protocol;
 };
 
+#define IEEE_8021QAZ_APP_SEL_MAX 255
+
 /**
  * struct dcb_peer_app_info - APP feature information sent by the peer
  *
@@ -425,6 +430,7 @@ enum ieee_attrs {
 enum ieee_attrs_app {
 	DCB_ATTR_IEEE_APP_UNSPEC,
 	DCB_ATTR_IEEE_APP,
+	DCB_ATTR_DCB_APP,
 	__DCB_ATTR_IEEE_APP_MAX
 };
 #define DCB_ATTR_IEEE_APP_MAX (__DCB_ATTR_IEEE_APP_MAX - 1)
diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index dc4fb699b56c..92c32bc11374 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -179,6 +179,33 @@ static const struct nla_policy dcbnl_featcfg_nest[DCB_FEATCFG_ATTR_MAX + 1] = {
 static LIST_HEAD(dcb_app_list);
 static DEFINE_SPINLOCK(dcb_lock);
 
+static enum ieee_attrs_app dcbnl_app_attr_type_get(u8 selector)
+{
+	switch (selector) {
+	case IEEE_8021QAZ_APP_SEL_ETHERTYPE:
+	case IEEE_8021QAZ_APP_SEL_STREAM:
+	case IEEE_8021QAZ_APP_SEL_DGRAM:
+	case IEEE_8021QAZ_APP_SEL_ANY:
+	case IEEE_8021QAZ_APP_SEL_DSCP:
+		return DCB_ATTR_IEEE_APP;
+	case DCB_APP_SEL_PCP:
+		return DCB_ATTR_DCB_APP;
+	default:
+		return DCB_ATTR_IEEE_APP_UNSPEC;
+	}
+}
+
+static bool dcbnl_app_attr_type_validate(enum ieee_attrs_app type)
+{
+	switch (type) {
+	case DCB_ATTR_IEEE_APP:
+	case DCB_ATTR_DCB_APP:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static struct sk_buff *dcbnl_newmsg(int type, u8 cmd, u32 port, u32 seq,
 				    u32 flags, struct nlmsghdr **nlhp)
 {
@@ -1116,8 +1143,9 @@ static int dcbnl_ieee_fill(struct sk_buff *skb, struct net_device *netdev)
 	spin_lock_bh(&dcb_lock);
 	list_for_each_entry(itr, &dcb_app_list, list) {
 		if (itr->ifindex == netdev->ifindex) {
-			err = nla_put(skb, DCB_ATTR_IEEE_APP, sizeof(itr->app),
-					 &itr->app);
+			enum ieee_attrs_app type =
+				dcbnl_app_attr_type_get(itr->app.selector);
+			err = nla_put(skb, type, sizeof(itr->app), &itr->app);
 			if (err) {
 				spin_unlock_bh(&dcb_lock);
 				return -EMSGSIZE;
@@ -1495,7 +1523,7 @@ static int dcbnl_ieee_set(struct net_device *netdev, struct nlmsghdr *nlh,
 		nla_for_each_nested(attr, ieee[DCB_ATTR_IEEE_APP_TABLE], rem) {
 			struct dcb_app *app_data;
 
-			if (nla_type(attr) != DCB_ATTR_IEEE_APP)
+			if (!dcbnl_app_attr_type_validate(nla_type(attr)))
 				continue;
 
 			if (nla_len(attr) < sizeof(struct dcb_app)) {
@@ -1556,7 +1584,7 @@ static int dcbnl_ieee_del(struct net_device *netdev, struct nlmsghdr *nlh,
 		nla_for_each_nested(attr, ieee[DCB_ATTR_IEEE_APP_TABLE], rem) {
 			struct dcb_app *app_data;
 
-			if (nla_type(attr) != DCB_ATTR_IEEE_APP)
+			if (!dcbnl_app_attr_type_validate(nla_type(attr)))
 				continue;
 			app_data = nla_data(attr);
 			if (ops->ieee_delapp)
-- 
2.34.1