net: dsa: xrs700x: reject unsupported HSR configurations

As discussed here:
https://lore.kernel.org/netdev/20240620090210.drop6jwh7e5qw556@skbuf/

the fact is that the xrs700x.c driver only supports offloading
HSR_PT_SLAVE_A and HSR_PT_SLAVE_B (which were the only port types at the
time the offload was written, _for this driver_).

Up until now, the API did not explicitly tell offloading drivers what
port has what role. So xrs700x can get confused and think that it can
support a configuration which it actually can't. There was a table in
the attached link which gave an example:

$ ip link add name hsr0 type hsr slave1 swp0 slave2 swp1 \
	interlink swp2 supervision 45 version 1

        HSR_PT_SLAVE_A    HSR_PT_SLAVE_B      HSR_PT_INTERLINK
 ----------------------------------------------------------------
 user
 space        0                 1                   2
 requests
 ----------------------------------------------------------------
 XRS700X
 driver       1                 2                   -
 understands

The switch would act as if the ring ports were swp1 and swp2.

Now that we have explicit hsr_get_port_type() API, let's use that to
work around the unintended semantical changes of the offloading API
brought by the introduction of interlink ports in HSR.

Fixes: 5055cccfc2d1 ("net: hsr: Provide RedBox support (HSR-SAN)")
Cc: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: George McCollister <george.mccollister@gmail.com>
Link: https://patch.msgid.link/20251130131657.65080-5-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/xrs700x/xrs700x.c b/drivers/net/dsa/xrs700x/xrs700x.c
index 4dbcc49a9e526f8aacc2e42b0a63bd114ed8f7d0..0a05f4156ef4d711430fb5ecc446c1e7fc2f86fa 100644 (file)
--- a/drivers/net/dsa/xrs700x/xrs700x.c
+++ b/drivers/net/dsa/xrs700x/xrs700x.c
@@ -566,6 +566,7 @@ static int xrs700x_hsr_join(struct dsa_switch *ds, int port,
        struct xrs700x *priv = ds->priv;
        struct net_device *user;
        int ret, i, hsr_pair[2];
+       enum hsr_port_type type;
        enum hsr_version ver;
        bool fwd = false;
 
@@ -589,6 +590,16 @@ static int xrs700x_hsr_join(struct dsa_switch *ds, int port,
                return -EOPNOTSUPP;
        }
 
+       ret = hsr_get_port_type(hsr, dsa_to_port(ds, port)->user, &type);
+       if (ret)
+               return ret;
+
+       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;
+       }
+
        dsa_hsr_foreach_port(dp, ds, hsr) {
                if (dp->index != port) {
                        partner = dp;