net: stmmac: Fixed mtu channged by cache aligned

[ Upstream commit 5b55299eed78538cc4746e50ee97103a1643249c ]

Since the original mtu is not used when the mtu is updated,
the mtu is aligned with cache, this will get an incorrect.
For example, if you want to configure the mtu to be 1500,
but mtu 1536 is configured in fact.

Fixed: eaf4fac478077 ("net: stmmac: Do not accept invalid MTU values")
Signed-off-by: David Wu <david.wu@rock-chips.com>
Link: https://lore.kernel.org/r/20210113034109.27865-1-david.wu@rock-chips.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 18c5a9bb6759c1184fd3933c71a577b6f8a95e2c..ce5d3e9e5dff434f5b871e3540c0378a9644ddb3 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3739,6 +3739,7 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
 {
        struct stmmac_priv *priv = netdev_priv(dev);
        int txfifosz = priv->plat->tx_fifo_size;
+       const int mtu = new_mtu;
 
        if (txfifosz == 0)
                txfifosz = priv->dma_cap.tx_fifo_size;
@@ -3756,7 +3757,7 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
        if ((txfifosz < new_mtu) || (new_mtu > BUF_SIZE_16KiB))
                return -EINVAL;
 
-       dev->mtu = new_mtu;
+       dev->mtu = mtu;
 
        netdev_update_features(dev);