Merge branch 'dsa-simple-hsr-offload'

Vladimir Oltean says:

====================
DSA simple HSR offload

Provide a "simple" form of HSR offload for 8 DSA drivers (just the
NETIF_F_HW_HSR_DUP feature) based on the fact that their taggers use the
dsa_xmit_port_mask() function. This is in patches 6-13/15.

The helpers per se are introduced in patch 5/15, and documented in patch
15/15. Patch 14/15 is another small (and related) documentation update.

For HSR interlink ports the offloading rules are not quite so clear, and
for now we completely reject the offload. We can revise that once we see
a full offload implementation and understand what is needed.

To reject the offload, we need to know the port type, and patch 2/15
helps with that.

xrs700x is another driver which should have rejected offload based on
port type (patch 4/15). This is a bug fix submitted through net-next due
to the extra API required to fix it. If necessary, it could also be
picked up separately for backporting.

There is also patch 3/15, which makes the HSR offload like the others
supported by DSA: if we fall back to the software implementation, don't
call port_hsr_leave(), because by definition there won't be anything to
do.

A slightly unrelated change is patch 1/15, but I noticed this along the
way, and if I were to submit it separately, it would conflict with this
work (it would appear in patch 12/15's context).

Most of the driver additions are trivial. By far the most complex was
ocelot (which I could test). Microchip ksz (which I cannot test, and did
not patch) would also have some complexity. Essentially, ksz_hsr_join()
could fall back to a partial offload through the simple helpers, if the
full offload is not possible. But keeping track of which offload kind
was used is necessary later in ksz_hsr_leave(). This is left as homework
for interested developers.

With this patch set, one can observe a 50% reduction in transmitted
traffic over HSR interfaces.
====================

Link: https://patch.msgid.link/20251130131657.65080-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 5b01a0e43ebe..a20efabe778f 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -9,6 +9,7 @@
 
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/if_hsr.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
@@ -1766,6 +1767,70 @@ bool dsa_mdb_present_in_other_db(struct dsa_switch *ds, int port,
 }
 EXPORT_SYMBOL_GPL(dsa_mdb_present_in_other_db);
 
+/* Helpers for switches without specific HSR offloads, but which can implement
+ * NETIF_F_HW_HSR_DUP because their tagger uses dsa_xmit_port_mask()
+ */
+int dsa_port_simple_hsr_validate(struct dsa_switch *ds, int port,
+				 struct net_device *hsr,
+				 struct netlink_ext_ack *extack)
+{
+	enum hsr_port_type type;
+	int err;
+
+	err = hsr_get_port_type(hsr, dsa_to_port(ds, port)->user, &type);
+	if (err)
+		return err;
+
+	if (type != HSR_PT_SLAVE_A && type != HSR_PT_SLAVE_B) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Only HSR slave ports can be offloaded");
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dsa_port_simple_hsr_validate);
+
+int dsa_port_simple_hsr_join(struct dsa_switch *ds, int port,
+			     struct net_device *hsr,
+			     struct netlink_ext_ack *extack)
+{
+	struct dsa_port *dp = dsa_to_port(ds, port), *other_dp;
+	int err;
+
+	err = dsa_port_simple_hsr_validate(ds, port, hsr, extack);
+	if (err)
+		return err;
+
+	dsa_hsr_foreach_port(other_dp, ds, hsr) {
+		if (other_dp != dp) {
+			dp->user->features |= NETIF_F_HW_HSR_DUP;
+			other_dp->user->features |= NETIF_F_HW_HSR_DUP;
+			break;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dsa_port_simple_hsr_join);
+
+int dsa_port_simple_hsr_leave(struct dsa_switch *ds, int port,
+			      struct net_device *hsr)
+{
+	struct dsa_port *dp = dsa_to_port(ds, port), *other_dp;
+
+	dsa_hsr_foreach_port(other_dp, ds, hsr) {
+		if (other_dp != dp) {
+			dp->user->features &= ~NETIF_F_HW_HSR_DUP;
+			other_dp->user->features &= ~NETIF_F_HW_HSR_DUP;
+			break;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dsa_port_simple_hsr_leave);
+
 static const struct dsa_stubs __dsa_stubs = {
 	.conduit_hwtstamp_validate = __dsa_conduit_hwtstamp_validate,
 };