xen/netfront: don't bug in case of too many frags

Commit 57f230ab04 ("xen/netfront: raise max number of slots in
xennet_get_responses()") raised the max number of allowed slots by one.
This seems to be problematic in some configurations with netback using
a larger MAX_SKB_FRAGS value (e.g. old Linux kernel with MAX_SKB_FRAGS
defined as 18 instead of nowadays 17).

Instead of BUG_ON() in this case just fall back to retransmission.

Fixes: 57f230ab04 ("xen/netfront: raise max number of slots in xennet_get_responses()")
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Juergen Gross 2018-09-11 09:04:48 +02:00 committed by David S. Miller
parent 22d0bd82cc
commit ad4f15dc2c

View File

@ -908,7 +908,11 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue,
BUG_ON(pull_to <= skb_headlen(skb));
__pskb_pull_tail(skb, pull_to - skb_headlen(skb));
}
BUG_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS);
if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) {
queue->rx.rsp_cons = ++cons;
kfree_skb(nskb);
return ~0U;
}
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
skb_frag_page(nfrag),
@ -1045,6 +1049,8 @@ static int xennet_poll(struct napi_struct *napi, int budget)
skb->len += rx->status;
i = xennet_fill_frags(queue, skb, &tmpq);
if (unlikely(i == ~0U))
goto err;
if (rx->flags & XEN_NETRXF_csum_blank)
skb->ip_summed = CHECKSUM_PARTIAL;