Commit 0f589967 authored by David Vrabel's avatar David Vrabel Committed by Konrad Rzeszutek Wilk

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: stable@vger.kernel.org
Reviewed-by: default avatarWei Liu <wei.liu2@citrix.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 454d5d88
...@@ -679,9 +679,7 @@ static void tx_add_credit(struct xenvif_queue *queue) ...@@ -679,9 +679,7 @@ static void tx_add_credit(struct xenvif_queue *queue)
* Allow a burst big enough to transmit a jumbo packet of up to 128kB. * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
* Otherwise the interface can seize up due to insufficient credit. * Otherwise the interface can seize up due to insufficient credit.
*/ */
max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size; max_burst = max(131072UL, queue->credit_bytes);
max_burst = min(max_burst, 131072UL);
max_burst = max(max_burst, queue->credit_bytes);
/* Take care that adding a new chunk of credit doesn't wrap to zero. */ /* Take care that adding a new chunk of credit doesn't wrap to zero. */
max_credit = queue->remaining_credit + queue->credit_bytes; max_credit = queue->remaining_credit + queue->credit_bytes;
......
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