[PATCH net-next v9 1/7] net: rtnetlink: add pacing_offload attribute to net_device

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

From: Willem de Bruijn <willemb@google.com>

Add a new flag to administratively control pacing offload.

The feature is disabled by default. That does not cause regressions, as no
driver advertises max_pacing_offload_horizon yet.

Also add NLA_REJECT for max_pacing_offload_horizon, in line with
other such read-only members of link-attrs.

Both fields can be read with

    ynl --family rt-link --do getlink \
        --json '{"ifname": "eth0"}' | grep pacing

And pacing offload enabled with

    ynl --family rt-link --do setlink \
        --json '{"ifname": "eth0", "pacing-offload": 1}'

Signed-off-by: Willem de Bruijn <willemb@google.com>

---

Changes
  v8 -> v9
    - rename pacing_offload_horizon to pacing_offload and make it boolean
    - leave max_pacing_offload_horizon as is (u64)
    - (minor) update ynl instructions
  v6 -> v7
    - commit-msg: update ynl invocation to installed version
  v5 -> v6
    - bring back fq_change update
    - commit-msg: reword absense of RTM_NEWLINK -> omitted from newlink
---
 Documentation/netlink/specs/rt-link.yaml      |  5 +++++
 .../networking/net_cachelines/net_device.rst  |  1 +
 include/linux/netdevice.h                     |  2 ++
 include/uapi/linux/if_link.h                  |  1 +
 net/core/rtnetlink.c                          | 22 +++++++++++++++++++
 5 files changed, 31 insertions(+)

diff --git a/Documentation/netlink/specs/rt-link.yaml b/Documentation/netlink/specs/rt-link.yaml
index 61ebb9a2bad5..d0559293b3b3 100644
--- a/Documentation/netlink/specs/rt-link.yaml
+++ b/Documentation/netlink/specs/rt-link.yaml
@@ -1089,6 +1089,10 @@ attribute-sets:
       -
         name: tailroom
         type: u16
+      -
+        name: pacing-offload
+        type: u32
+        doc: Enable EDT pacing offload (0 - disabled, 1 - enabled).
   -
     name: prop-list-link-attrs
     subset-of: link-attrs
@@ -2557,6 +2561,7 @@ operations:
             - devlink-port
             - gso-ipv4-max-size
             - gro-ipv4-max-size
+            - pacing-offload
       dump:
         request:
           value: 18
diff --git a/Documentation/networking/net_cachelines/net_device.rst b/Documentation/networking/net_cachelines/net_device.rst
index 512f6d6fa3d8..8eceaa80b686 100644
--- a/Documentation/networking/net_cachelines/net_device.rst
+++ b/Documentation/networking/net_cachelines/net_device.rst
@@ -11,6 +11,7 @@ Type                                Name                        fastpath_tx_acce
 unsigned_long:32                    priv_flags                  read_mostly                             __dev_queue_xmit(tx)
 unsigned_long:1                     lltx                        read_mostly                             HARD_TX_LOCK,HARD_TX_TRYLOCK,HARD_TX_UNLOCK(tx)
 unsigned_long:2                     netmem_tx:2;                read_mostly
+unsigned_long:1                     pacing_offload              read_mostly                             sch_fq
 char                                name[16]
 struct netdev_name_node*            name_node
 struct dev_ifalias*                 ifalias
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 707b2e51c2b9..1f0710eef185 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1840,6 +1840,7 @@ enum netdev_reg_state {
  *			drivers. Mainly used by logical interfaces, such as
  *			bonding and tunnels
  *	@netmem_tx:	device netmem TX mode
+ *	@pacing_offload: enable EDT pacing offload.
  *
  *	@name:	This is the first field of the "visible" part of this structure
  *		(i.e. as seen by users in the "Space.c" file).  It is the name
@@ -2170,6 +2171,7 @@ struct net_device {
 		unsigned long		priv_flags:32;
 		unsigned long		lltx:1;
 		unsigned long		netmem_tx:2;
+		unsigned long		pacing_offload:1;
 	);
 	const struct net_device_ops *netdev_ops;
 	const struct header_ops *header_ops;
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 43cecca49f01..245b36204525 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -381,6 +381,7 @@ enum {
 	IFLA_NETNS_IMMUTABLE,
 	IFLA_HEADROOM,
 	IFLA_TAILROOM,
+	IFLA_PACING_OFFLOAD,
 	__IFLA_MAX
 };
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 81c5a6104dea..aeccfa814f40 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1396,6 +1396,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
 	       + rtnl_devlink_port_size(dev)
 	       + rtnl_dpll_pin_size()
 	       + nla_total_size(8)  /* IFLA_MAX_PACING_OFFLOAD_HORIZON */
+	       + nla_total_size(4)  /* IFLA_PACING_OFFLOAD */
 	       + nla_total_size(2)  /* IFLA_HEADROOM */
 	       + nla_total_size(2)  /* IFLA_TAILROOM */
 	       + rtnl_dev_parent_size(dev)
@@ -2176,6 +2177,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
 			READ_ONCE(dev->tso_max_segs)) ||
 	    nla_put_uint(skb, IFLA_MAX_PACING_OFFLOAD_HORIZON,
 			 READ_ONCE(dev->max_pacing_offload_horizon)) ||
+	    nla_put_u32(skb, IFLA_PACING_OFFLOAD,
+			dev->pacing_offload) ||
 #ifdef CONFIG_RPS
 	    nla_put_u32(skb, IFLA_NUM_RX_QUEUES,
 			READ_ONCE(dev->num_rx_queues)) ||
@@ -2344,9 +2347,11 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
 	[IFLA_ALLMULTI]		= { .type = NLA_REJECT },
 	[IFLA_GSO_IPV4_MAX_SIZE]	= NLA_POLICY_MIN(NLA_U32, MAX_TCP_HEADER + 1),
 	[IFLA_GRO_IPV4_MAX_SIZE]	= { .type = NLA_U32 },
+	[IFLA_MAX_PACING_OFFLOAD_HORIZON] = { .type = NLA_REJECT },
 	[IFLA_NETNS_IMMUTABLE]	= { .type = NLA_REJECT },
 	[IFLA_HEADROOM]		= { .type = NLA_REJECT },
 	[IFLA_TAILROOM]		= { .type = NLA_REJECT },
+	[IFLA_PACING_OFFLOAD]	= NLA_POLICY_MAX(NLA_U32, 1),
 };
 
 static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
@@ -2820,6 +2825,14 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
 		return -EINVAL;
 	}
 
+	if (tb[IFLA_PACING_OFFLOAD]) {
+		if (nla_get_u32(tb[IFLA_PACING_OFFLOAD]) &&
+		    !dev->max_pacing_offload_horizon) {
+			NL_SET_ERR_MSG(extack, "pacing offload not supported by device");
+			return -EOPNOTSUPP;
+		}
+	}
+
 	if (tb[IFLA_AF_SPEC]) {
 		struct nlattr *af;
 		int rem, err;
@@ -3337,6 +3350,15 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
 		}
 	}
 
+	if (tb[IFLA_PACING_OFFLOAD]) {
+		bool val = nla_get_u32(tb[IFLA_PACING_OFFLOAD]);
+
+		if (dev->pacing_offload != val) {
+			dev->pacing_offload = val;
+			status |= DO_SETLINK_MODIFIED;
+		}
+	}
+
 	if (tb[IFLA_OPERSTATE])
 		set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
 
-- 
2.55.0.1007.g17ff1f9808-goog