xen-netback: don't use last request to determine minimum Tx credit
The last from guest transmitted request gives no indication about the
minimum amount of credit that the guest might need to send a packet
since the last packet might have been a small one.
Instead allow for the worst case 128 KiB packet.
This is part of XSA155.
CC: [email protected]
Reviewed-by: Wei Liu <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index e481f37..b683581 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -679,9 +679,7 @@
* Allow a burst big enough to transmit a jumbo packet of up to 128kB.
* Otherwise the interface can seize up due to insufficient credit.
*/
- max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size;
- max_burst = min(max_burst, 131072UL);
- max_burst = max(max_burst, queue->credit_bytes);
+ max_burst = max(131072UL, queue->credit_bytes);
/* Take care that adding a new chunk of credit doesn't wrap to zero. */
max_credit = queue->remaining_credit + queue->credit_bytes;
