net: sh_eth: fix skb_over_panic happen

When this GETHER controller received a large frame (about 1800 bytes
or more), skb_over_panic() happened. This is because the previous
driver set the RFLR to 0x1000 (4096 bytes) and the skb allocate size
is smaller than 4096 bytes. So, the controller accepted such a frame.

The controller can discard a large frame by the RFLR setting.
So, the patch modifies the value of RFLR to mtu + ETH_HLEN +
VLAN_HLEN + ETH_FCS_LEN.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -38,6 +38,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/ethtool.h>
+#include <linux/if_vlan.h>
 #include <linux/sh_eth.h>
 
 #include "sh_eth.h"
@@ -817,7 +818,8 @@ static int sh_eth_dev_init(struct net_device *ndev)
 		sh_eth_write(ndev, 0, TRIMD);
 
 	/* Recv frame limit set register */
-	sh_eth_write(ndev, RFLR_VALUE, RFLR);
+	sh_eth_write(ndev, ndev->mtu + ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN,
+		     RFLR);
 
 	sh_eth_write(ndev, sh_eth_read(ndev, EESR), EESR);
 	sh_eth_write(ndev, mdp->cd->eesipr_value, EESIPR);

drivers/net/ethernet/renesas/sh_eth.h

@@ -575,9 +575,6 @@ enum RPADIR_BIT {
 	RPADIR_PADR = 0x0003f,
 };
 
-/* RFLR */
-#define RFLR_VALUE 0x1000
-
 /* FDR */
 #define DEFAULT_FDR_INIT	0x00000707