net: ethtool: Fix symmetric-xor RSS RX flow hash check

Commit 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")
adds a check to the ethtool set_rxnfc operation, which checks the RX
flow hash if the flag RXH_XFRM_SYM_XOR is set. This flag is introduced
with the same commit. It calls the ethtool get_rxfh operation to get the
RX flow hash data. If get_rxfh is not supported, then EOPNOTSUPP is
returned.

There are driver like tsnep, macb, asp2, genet, gianfar, mtk, ... which
support the ethtool operation set_rxnfc but not get_rxfh. This results
in EOPNOTSUPP returned by ethtool_set_rxnfc() without actually calling
the ethtool operation set_rxnfc. Thus, set_rxnfc got broken for all
these drivers.

Check RX flow hash in ethtool_set_rxnfc() only if driver supports RX
flow hash.

Fixes: 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")
Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Link: https://lore.kernel.org/r/20231226205536.32003-1-gerhard@engleder-embedded.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 4c4f46dfc251b82b2cf350495e7f6e13a77a850e..4bc9a2a07bbb3faafc6dcaecacb18d8d1951217f 100644 (file)
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -973,32 +973,35 @@ static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
                                                u32 cmd, void __user *useraddr)
 {
        const struct ethtool_ops *ops = dev->ethtool_ops;
-       struct ethtool_rxfh_param rxfh = {};
        struct ethtool_rxnfc info;
        size_t info_size = sizeof(info);
        int rc;
 
-       if (!ops->set_rxnfc || !ops->get_rxfh)
+       if (!ops->set_rxnfc)
                return -EOPNOTSUPP;
 
        rc = ethtool_rxnfc_copy_struct(cmd, &info, &info_size, useraddr);
        if (rc)
                return rc;
 
-       rc = ops->get_rxfh(dev, &rxfh);
-       if (rc)
-               return rc;
+       if (ops->get_rxfh) {
+               struct ethtool_rxfh_param rxfh = {};
 
-       /* Sanity check: if symmetric-xor is set, then:
-        * 1 - no other fields besides IP src/dst and/or L4 src/dst
-        * 2 - If src is set, dst must also be set
-        */
-       if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
-           ((info.data & ~(RXH_IP_SRC | RXH_IP_DST |
-                           RXH_L4_B_0_1 | RXH_L4_B_2_3)) ||
-            (!!(info.data & RXH_IP_SRC) ^ !!(info.data & RXH_IP_DST)) ||
-            (!!(info.data & RXH_L4_B_0_1) ^ !!(info.data & RXH_L4_B_2_3))))
-               return -EINVAL;
+               rc = ops->get_rxfh(dev, &rxfh);
+               if (rc)
+                       return rc;
+
+               /* Sanity check: if symmetric-xor is set, then:
+                * 1 - no other fields besides IP src/dst and/or L4 src/dst
+                * 2 - If src is set, dst must also be set
+                */
+               if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
+                   ((info.data & ~(RXH_IP_SRC | RXH_IP_DST |
+                                   RXH_L4_B_0_1 | RXH_L4_B_2_3)) ||
+                    (!!(info.data & RXH_IP_SRC) ^ !!(info.data & RXH_IP_DST)) ||
+                    (!!(info.data & RXH_L4_B_0_1) ^ !!(info.data & RXH_L4_B_2_3))))
+                       return -EINVAL;
+       }
 
        rc = ops->set_rxnfc(dev, &info);
        if (rc)