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net: fix usbnet_receive() packet drops 

The USB network interface has a single buffer which the guest reads
from.  This patch prevents multiple calls to usbnet_receive() from
clobbering the input buffer.  Instead we queue packets until buffer
space becomes available again.

This is inspired by virtio-net and e1000 rxbuf handling.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Stefan Hajnoczi 2012-08-24 13:37:29 +01:00 committed by Stefan Hajnoczi
parent f237ddbb89
commit 190563f9a9
1 changed files with 16 additions and 3 deletions
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19
hw/usb/dev-network.c
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@ -1001,6 +1001,13 @@ static int rndis_keepalive_response(USBNetState *s,
return 0;
}
/* Prepare to receive the next packet */
static void usb_net_reset_in_buf(USBNetState *s)
{
s->in_ptr = s->in_len = 0;
qemu_flush_queued_packets(&s->nic->nc);
}
static int rndis_parse(USBNetState *s, uint8_t *data, int length)
{
uint32_t msg_type;
@ -1025,7 +1032,8 @@ static int rndis_parse(USBNetState *s, uint8_t *data, int length)
case RNDIS_RESET_MSG:
rndis_clear_responsequeue(s);
s->out_ptr = s->in_ptr = s->in_len = 0;
s->out_ptr = 0;
usb_net_reset_in_buf(s);
return rndis_reset_response(s, (rndis_reset_msg_type *) data);
case RNDIS_KEEPALIVE_MSG:
@ -1135,7 +1143,7 @@ static int usb_net_handle_datain(USBNetState *s, USBPacket *p)
int ret = USB_RET_NAK;
if (s->in_ptr > s->in_len) {
s->in_ptr = s->in_len = 0;
usb_net_reset_in_buf(s);
ret = USB_RET_NAK;
return ret;
}
@ -1152,7 +1160,7 @@ static int usb_net_handle_datain(USBNetState *s, USBPacket *p)
if (s->in_ptr >= s->in_len &&
(is_rndis(s) || (s->in_len & (64 - 1)) || !ret)) {
/* no short packet necessary */
s->in_ptr = s->in_len = 0;
usb_net_reset_in_buf(s);
}
#ifdef TRAFFIC_DEBUG
@ -1263,6 +1271,11 @@ static ssize_t usbnet_receive(NetClientState *nc, const uint8_t *buf, size_t siz
return -1;
}
/* Only accept packet if input buffer is empty */
if (s->in_len > 0) {
return 0;
}
if (is_rndis(s)) {
struct rndis_packet_msg_type *msg;