* [PATCH net] gso: Validate assumption of frag_list segementation
@ 2017-04-19 18:26 ilant
2017-04-21 17:30 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: ilant @ 2017-04-19 18:26 UTC (permalink / raw)
To: David Miller
Cc: netdev, Alexander Duyck, Eric Dumazet, Steffen Klassert,
Boris Pismenny, Ilya Lesokhin, Ilan Tayari
From: Ilan Tayari <ilant@mellanox.com>
Commit 07b26c9454a2 ("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.
Change-Id: Ia03983f4a47b6534dd987d7a2aad96d54d46d212
Fixes: 07b26c9454a2 ("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>
---
net/core/skbuff.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 35c1e2460206..f86bf69cfb8d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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))
goto normal;
len -= iter->len;
}
+
+ if (len != frag_len)
+ goto normal;
}
/* GSO partial only requires that we trim off any excess that
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] gso: Validate assumption of frag_list segementation
2017-04-19 18:26 [PATCH net] gso: Validate assumption of frag_list segementation ilant
@ 2017-04-21 17:30 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2017-04-21 17:30 UTC (permalink / raw)
To: ilant
Cc: netdev, alexander.h.duyck, eric.dumazet, steffen.klassert, borisp, ilyal
From: <ilant@mellanox.com>
Date: Wed, 19 Apr 2017 21:26:07 +0300
> From: Ilan Tayari <ilant@mellanox.com>
>
> Commit 07b26c9454a2 ("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.
>
> Change-Id: Ia03983f4a47b6534dd987d7a2aad96d54d46d212
> Fixes: 07b26c9454a2 ("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>
Applied.
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2017-04-21 17:30 ` David Miller
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