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Commit 8b7a7048 authored by David Woodhouse's avatar David Woodhouse Committed by David S. Miller
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8139cp: Fix GSO MSS handling 



When fixing the TSO support I noticed we just mask ->gso_size with the
MSSMask value and don't care about the consequences.

Provide a .ndo_features_check() method which drops the NETIF_F_TSO
feature for any skb which would exceed the maximum, and thus forces it
to be segmented by software.

Then we can stop the masking in cp_start_xmit(), and just WARN if the
maximum is exceeded, which should now never happen.

Finally, Francois Romieu noticed that we didn't even have the right
value for MSSMask anyway; it should be 0x7ff (11 bits) not 0xfff.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5a58f227

drivers/net/ethernet/realtek/8139cp.c

+18 −2
Original line number Diff line number Diff line
@@ -175,7 +175,7 @@ enum { 
	LastFrag	= (1 << 28), /* Final segment of a packet */

	LargeSend	= (1 << 27), /* TCP Large Send Offload (TSO) */

	MSSShift	= 16,	     /* MSS value position */

	MSSMask		= 0xfff,     /* MSS value: 11 bits */

	MSSMask		= 0x7ff,     /* MSS value: 11 bits */

	TxError		= (1 << 23), /* Tx error summary */

	RxError		= (1 << 20), /* Rx error summary */

	IPCS		= (1 << 18), /* Calculate IP checksum */
@@ -754,10 +754,16 @@ static netdev_tx_t cp_start_xmit (struct sk_buff *skb, 
	eor = (entry == (CP_TX_RING_SIZE - 1)) ? RingEnd : 0;

	mss = skb_shinfo(skb)->gso_size;



	if (mss > MSSMask) {

		WARN_ONCE(1, "Net bug: GSO size %d too large for 8139CP\n",

			  mss);

		goto out_dma_error;

	}



	opts2 = cpu_to_le32(cp_tx_vlan_tag(skb));

	opts1 = DescOwn;

	if (mss)

		opts1 |= LargeSend | ((mss & MSSMask) << MSSShift);

		opts1 |= LargeSend | (mss << MSSShift);

	else if (skb->ip_summed == CHECKSUM_PARTIAL) {

		const struct iphdr *ip = ip_hdr(skb);

		if (ip->protocol == IPPROTO_TCP)
@@ -1852,6 +1858,15 @@ static void cp_set_d3_state (struct cp_private *cp) 
	pci_set_power_state (cp->pdev, PCI_D3hot);

}



static netdev_features_t cp_features_check(struct sk_buff *skb,

					   struct net_device *dev,

					   netdev_features_t features)

{

	if (skb_shinfo(skb)->gso_size > MSSMask)

		features &= ~NETIF_F_TSO;



	return vlan_features_check(skb, features);

}

static const struct net_device_ops cp_netdev_ops = {

	.ndo_open		= cp_open,

	.ndo_stop		= cp_close,
@@ -1864,6 +1879,7 @@ static const struct net_device_ops cp_netdev_ops = { 
	.ndo_tx_timeout		= cp_tx_timeout,

	.ndo_set_features	= cp_set_features,

	.ndo_change_mtu		= cp_change_mtu,

	.ndo_features_check	= cp_features_check,



#ifdef CONFIG_NET_POLL_CONTROLLER

	.ndo_poll_controller	= cp_poll_controller,