From: Andy Roulin aroulin@nvidia.com
[ Upstream commit e847c7675e19ef344913724dc68f83df31ad6a17 ]
If the number of lanes was forced and then subsequently the user omits this parameter, the ksettings->lanes is reset. The driver should then reset the number of lanes to the device's default for the specified speed.
However, although the ksettings->lanes is set to 0, the mod variable is not set to true to indicate the driver and userspace should be notified of the changes.
The consequence is that the same ethtool operation will produce different results based on the initial state.
If the initial state is: $ ethtool swp1 | grep -A 3 'Speed: ' Speed: 500000Mb/s Lanes: 2 Duplex: Full Auto-negotiation: on
then executing 'ethtool -s swp1 speed 50000 autoneg off' will yield: $ ethtool swp1 | grep -A 3 'Speed: ' Speed: 500000Mb/s Lanes: 2 Duplex: Full Auto-negotiation: off
While if the initial state is: $ ethtool swp1 | grep -A 3 'Speed: ' Speed: 500000Mb/s Lanes: 1 Duplex: Full Auto-negotiation: off
executing the same 'ethtool -s swp1 speed 50000 autoneg off' results in: $ ethtool swp1 | grep -A 3 'Speed: ' Speed: 500000Mb/s Lanes: 1 Duplex: Full Auto-negotiation: off
This patch fixes this behavior. Omitting lanes will always results in the driver choosing the default lane width for the chosen speed. In this scenario, regardless of the initial state, the end state will be, e.g.,
$ ethtool swp1 | grep -A 3 'Speed: ' Speed: 500000Mb/s Lanes: 2 Duplex: Full Auto-negotiation: off
Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes") Signed-off-by: Andy Roulin aroulin@nvidia.com Reviewed-by: Danielle Ratson danieller@nvidia.com Reviewed-by: Ido Schimmel idosch@nvidia.com Link: https://lore.kernel.org/r/ac238d6b-8726-8156-3810-6471291dbc7f@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ethtool/linkmodes.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/ethtool/linkmodes.c b/net/ethtool/linkmodes.c index f9eda596f3014..3d05b9bf34854 100644 --- a/net/ethtool/linkmodes.c +++ b/net/ethtool/linkmodes.c @@ -277,11 +277,12 @@ static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb, "lanes configuration not supported by device"); return -EOPNOTSUPP; } - } else if (!lsettings->autoneg) { - /* If autoneg is off and lanes parameter is not passed from user, - * set the lanes parameter to 0. + } else if (!lsettings->autoneg && ksettings->lanes) { + /* If autoneg is off and lanes parameter is not passed from user but + * it was defined previously then set the lanes parameter to 0. */ ksettings->lanes = 0; + *mod = true; }
ret = ethnl_update_bitset(ksettings->link_modes.advertising,