net: fix ethtool->set_flags not intended -EINVAL return value

After commit d5dbda23804156ae6f35025ade5307a49d1db6d7 "ethtool: Add
support for vlan accleration.", drivers that have NETIF_F_HW_VLAN_TX,
and/or NETIF_F_HW_VLAN_RX feature, but do not allow enable/disable vlan
acceleration via ethtool set_flags, always return -EINVAL from that
function. Fix by returning -EINVAL only if requested features do not
match current settings and can not be changed by driver.

Change any driver that define ethtool->set_flags to use
ethtool_invalid_flags() to avoid similar problems in the future
(also on drivers that do not have the problem).

Tested with modified (to reproduce this bug) myri10ge driver.

Cc: stable@kernel.org # 2.6.37+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 1 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 24bd57493c0d..74ead9eca126 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -141,9 +141,24 @@ u32 ethtool_op_get_flags(struct net_device *dev)
 }
 EXPORT_SYMBOL(ethtool_op_get_flags);
 
+/* Check if device can enable (or disable) particular feature coded in "data"
+ * argument. Flags "supported" describe features that can be toggled by device.
+ * If feature can not be toggled, it state (enabled or disabled) must match
+ * hardcoded device features state, otherwise flags are marked as invalid.
+ */
+bool ethtool_invalid_flags(struct net_device *dev, u32 data, u32 supported)
+{
+        u32 features = dev->features & flags_dup_features;
+        /* "data" can contain only flags_dup_features bits,
+         * see __ethtool_set_flags */
+
+        return (features & ~supported) != (data & ~supported);
+}
+EXPORT_SYMBOL(ethtool_invalid_flags);
+
 int ethtool_op_set_flags(struct net_device *dev, u32 data, u32 supported)
 {
-        if (data & ~supported)
+        if (ethtool_invalid_flags(dev, data, supported))
                 return -EINVAL;
 
         dev->features = ((dev->features & ~flags_dup_features) |