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 4ac507b4d101924b5b6c36bb5f857014add35fed..76d4b8e6ac3e834c804176a761fa868aa36e0cfe 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3596,6 +3596,7 @@ 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;
@@ -3613,7 +3614,7 @@ 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);