From: Jonathan McDowell <noodles@xxxxxxxx> [ Upstream commit 99cab7107d914a71c57f5a4e6d34292425fbbb61 ] The qca8k only supports a switch-wide MTU setting, and the code to take the max of all ports was only looking at the port currently being set. Fix to examine all ports. Reported-by: DENG Qingfang <dqfext@xxxxxxxxx> Fixes: f58d2598cf70 ("net: dsa: qca8k: implement the port MTU callbacks") Signed-off-by: Jonathan McDowell <noodles@xxxxxxxx> Reviewed-by: Andrew Lunn <andrew@xxxxxxx> Link: https://lore.kernel.org/r/20201030183315.GA6736@xxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/dsa/qca8k.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/net/dsa/qca8k.c +++ b/drivers/net/dsa/qca8k.c @@ -1219,8 +1219,8 @@ qca8k_port_change_mtu(struct dsa_switch priv->port_mtu[port] = new_mtu; for (i = 0; i < QCA8K_NUM_PORTS; i++) - if (priv->port_mtu[port] > mtu) - mtu = priv->port_mtu[port]; + if (priv->port_mtu[i] > mtu) + mtu = priv->port_mtu[i]; /* Include L2 header / FCS length */ qca8k_write(priv, QCA8K_MAX_FRAME_SIZE, mtu + ETH_HLEN + ETH_FCS_LEN);