gso: Validate assumption of frag_list segementation (7a7a9bd7) · Commits · 戴 / test

Commit ("gso: Support partial splitting at the frag_list pointer") assumes that all SKBs in a frag_list (except maybe the last one) contain the same amount of GSO payload. This assumption is not always correct, resulting in the following warning message in the log: skb_segment: too many frags For example, mlx5 driver in Striding RQ mode creates some RX SKBs with one frag, and some with 2 frags. After GRO, the frag_list SKBs end up having different amounts of payload. If this frag_list SKB is then forwarded, the aforementioned assumption is violated. Validate the assumption, and fall back to software GSO if it not true. Fixes: ("gso: Support partial splitting at the frag_list pointer") Signed-off-by:

Ilan Tayari <ilant@mellanox.com> Signed-off-by:

Ilya Lesokhin <ilyal@mellanox.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/skbuff.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -3082,22 +3082,32 @@ struct sk_buff skb_segment(struct sk_buff head_skb,
		if (sg && csum && (mss != GSO_BY_FRAGS)) {
		if (!(features & NETIF_F_GSO_PARTIAL)) {
		struct sk_buff *iter;
		unsigned int frag_len;

		if (!list_skb \|\|
		!net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
		goto normal;

		/* Split the buffer at the frag_list pointer.
		* This is based on the assumption that all
		* buffers in the chain excluding the last
		* containing the same amount of data.
		/* If we get here then all the required
		* GSO features except frag_list are supported.
		* Try to split the SKB to multiple GSO SKBs
		* with no frag_list.
		* Currently we can do that only when the buffers don't
		* have a linear part and all the buffers except
		* the last are of the same length.
		*/
		frag_len = list_skb->len;
		skb_walk_frags(head_skb, iter) {
		if (frag_len != iter->len && iter->next)
		goto normal;
		if (skb_headlen(iter) && !iter->head_frag)
		goto normal;

		len -= iter->len;
		}

		if (len != frag_len)
		goto normal;
		}

		/* GSO partial only requires that we trim off any excess that

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