net: relax expensive skb_unclone() in iptunnel_handle_offloads() (9580bf2e) · Commits · 戴 / test

Locally generated TCP GSO packets having to go through a GRE/SIT/IPIP tunnel have to go through an expensive skb_unclone() Reallocating skb->head is a lot of work. Test should really check if a 'real clone' of the packet was done. TCP does not care if the original gso_type is changed while the packet travels in the stack. This adds skb_header_unclone() which is a variant of skb_clone() using skb_header_cloned() check instead of skb_cloned(). This variant can probably be used from other points. Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -1325,6 +1325,16 @@ static inline int skb_header_cloned(const struct sk_buff *skb)
		return dataref != 1;
		}

		static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
		{
		might_sleep_if(gfpflags_allow_blocking(pri));

		if (skb_header_cloned(skb))
		return pskb_expand_head(skb, 0, 0, pri);

		return 0;
		}

		/**
		* skb_header_release - release reference to header
		* @skb: buffer to operate on

net/ipv4/ip_tunnel_core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -157,7 +157,7 @@ int iptunnel_handle_offloads(struct sk_buff *skb,
		}

		if (skb_is_gso(skb)) {
		err = skb_unclone(skb, GFP_ATOMIC);
		err = skb_header_unclone(skb, GFP_ATOMIC);
		if (unlikely(err))
		return err;
		skb_shinfo(skb)->gso_type \|= gso_type_mask;

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