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Commit ec475623 authored by Steve Glendinning's avatar Steve Glendinning Committed by David S. Miller
Browse files

smsc95xx: fix transmission where ZLP is expected 



Usbnet framework assumes USB hardware doesn't handle zero length
packets, but SMSC LAN95xx requires these to be sent for correct
operation.

This patch fixes an easily reproducible tx lockup when sending a frame
that results in exactly 512 bytes in a USB transmission (e.g. a UDP
frame with 458 data bytes, due to IP headers and our USB headers).  It
adds an extra flag to usbnet for the hardware driver to indicate that
it can handle and requires the zero length packets.

This patch should not affect other usbnet users, please also consider
for -stable.

Signed-off-by: default avatarSteve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 36989b90

drivers/net/usb/smsc95xx.c

+1 −1
Original line number Diff line number Diff line
@@ -1227,7 +1227,7 @@ static const struct driver_info smsc95xx_info = { 
	.rx_fixup	= smsc95xx_rx_fixup,

	.tx_fixup	= smsc95xx_tx_fixup,

	.status		= smsc95xx_status,

	.flags		= FLAG_ETHER,

	.flags		= FLAG_ETHER | FLAG_SEND_ZLP,

};



static const struct usb_device_id products[] = {

drivers/net/usb/usbnet.c

+1 −1
Original line number Diff line number Diff line
@@ -1049,7 +1049,7 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, 
	 * NOTE:  strictly conforming cdc-ether devices should expect

	 * the ZLP here, but ignore the one-byte packet.

	 */

	if ((length % dev->maxpacket) == 0) {

	if (!(info->flags & FLAG_SEND_ZLP) && (length % dev->maxpacket) == 0) {

		urb->transfer_buffer_length++;

		if (skb_tailroom(skb)) {

			skb->data[skb->len] = 0;

include/linux/usb/usbnet.h

+1 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ struct driver_info { 
#define FLAG_FRAMING_AX 0x0040		/* AX88772/178 packets */

#define FLAG_WLAN	0x0080		/* use "wlan%d" names */

#define FLAG_AVOID_UNLINK_URBS 0x0100	/* don't unlink urbs at usbnet_stop() */

#define FLAG_SEND_ZLP	0x0200		/* hw requires ZLPs are sent */





	/* init device ... can sleep, or cause probe() failure */