Commit ad4f15dc authored Sep 11, 2018 by Juergen Gross Committed by David S. Miller Sep 13, 2018

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



Commit 57f230ab ("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: 57f230ab ("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>

parent 22d0bd82

drivers/net/xen-netfront.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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;