Messages in this thread | | | From | Eric Dumazet <> | Date | Fri, 27 Jul 2018 20:13:19 -0700 | Subject | Re: [PATCH net-next 2/2] tcp: propagate GSO to the new skb built in tcp collapse |
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On Fri, Jul 27, 2018 at 8:02 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > Currently the collapsed SKB doesn't propagate the GSO information to the > new SKB. > The GSO should be propagated for better tracking, i.e. when this SKB is > dropped we could know how many network segments are dropped.
What is "the GSO" ?
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > net/ipv4/tcp_input.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index 90f83eb..af52e4e 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -4893,6 +4893,8 @@ void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb) > if (!nskb) > break; > > + skb_shinfo(nskb)->gso_size = skb_shinfo(skb)->gso_size; > + skb_shinfo(nskb)->gso_type = skb_shinfo(skb)->gso_type;
Why gso_size and gso_type are important ?
Where later in the stack these values are used ?
> memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); > #ifdef CONFIG_TLS_DEVICE > nskb->decrypted = skb->decrypted; > @@ -4906,18 +4908,24 @@ void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb) > > /* Copy data, releasing collapsed skbs. */ > while (copy > 0) { > - int offset = start - TCP_SKB_CB(skb)->seq; > int size = TCP_SKB_CB(skb)->end_seq - start; > + int offset = start - TCP_SKB_CB(skb)->seq;
> > BUG_ON(offset < 0); > if (size > 0) { > - size = min(copy, size); > + if (copy >= size) > + skb_shinfo(nskb)->gso_segs += > + max_t(u16, 1, skb_shinfo(skb)->gso_segs); > + else > + size = copy; > +
So... what happens if copy was partial ?
Your patch does not really fix the uncertainty, it merely shifts it a bit.
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