* [PATCH] net: Set trailer iff skb1 is the last one
@ 2020-08-27 11:29 Miaohe Lin
2020-08-27 11:35 ` Eric Dumazet
0 siblings, 1 reply; 2+ messages in thread
From: Miaohe Lin @ 2020-08-27 11:29 UTC (permalink / raw)
To: davem, kuba, pshelar, fw, martin.varghese, edumazet, dcaratti,
steffen.klassert, pabeni, shmulik, kyk.segfault
Cc: netdev, linux-kernel, linmiaohe
Set trailer iff skb1 is the skbuff where the tailbits space begins.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
net/core/skbuff.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 0b24aed04060..18ed56316e56 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4488,8 +4488,9 @@ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
skb1 = skb2;
}
elt++;
- *trailer = skb1;
skb_p = &skb1->next;
+ if (!*skb_p)
+ *trailer = skb1;
}
return elt;
--
2.19.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] net: Set trailer iff skb1 is the last one
2020-08-27 11:29 [PATCH] net: Set trailer iff skb1 is the last one Miaohe Lin
@ 2020-08-27 11:35 ` Eric Dumazet
0 siblings, 0 replies; 2+ messages in thread
From: Eric Dumazet @ 2020-08-27 11:35 UTC (permalink / raw)
To: Miaohe Lin
Cc: David Miller, Jakub Kicinski, Pravin B Shelar, Florian Westphal,
martin.varghese, Davide Caratti, Steffen Klassert, Paolo Abeni,
shmulik, kyk.segfault, netdev, LKML
On Thu, Aug 27, 2020 at 4:31 AM Miaohe Lin <linmiaohe@huawei.com> wrote:
>
> Set trailer iff skb1 is the skbuff where the tailbits space begins.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> net/core/skbuff.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 0b24aed04060..18ed56316e56 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4488,8 +4488,9 @@ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
> skb1 = skb2;
> }
> elt++;
> - *trailer = skb1;
> skb_p = &skb1->next;
> + if (!*skb_p)
> + *trailer = skb1;
>
Why is adding a conditional test going to help ?
cpu will have hard time predicting this one, I doubt this kind of
change is a win.
^ permalink raw reply [flat|nested] 2+ messages in thread
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