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 d5ebaf62d12fe068c4d88acb6e7da50eb26ad6e3..a7b30f0605362e1b73e6a9eeb0d06263372c64b0 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3613,6 +3613,7 @@ 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;
@@ -3630,7 +3631,7 @@ 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);