Re: [Xen-devel] [PATCH 2/6] xen-netfront: reduce gso_max_size to account for ethernet header
From: David Vrabel <hidden>
Date: 2013-03-25 14:24:15
On 25/03/13 11:08, Wei Liu wrote:
The maximum packet including ethernet header that can be handled by netfront / netback wire format is 65535. Reduce gso_max_size accordingly. Drop skb and print warning when skb->len > 65535. This can 1) save the effort to send malformed packet to netback, 2) help spotting misconfiguration of netfront in the future.
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quoted hunk ↗ jump to hunk
--- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c@@ -547,6 +547,18 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev) unsigned int len = skb_headlen(skb); unsigned long flags; + /* Wire format of xen_netif_tx_request only supports skb->len + * < 64K, because size field in xen_netif_tx_request is + * uint16_t. If skb->len is too big, drop it and alert user about + * misconfiguration. + */ + if (unlikely(skb->len >= (uint16_t)(~0))) {
Suggest a #define for this maximum added to include/xen/interface/io/netif.h David