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: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/realtek/8139cp.c b/drivers/net/ethernet/realtek/8139cp.c
index e5173f3..deae10d 100644
--- a/drivers/net/ethernet/realtek/8139cp.c
+++ b/drivers/net/ethernet/realtek/8139cp.c
@@ -175,7 +175,7 @@
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 @@
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 @@
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 @@
.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,