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Commit 9580bf2e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: relax expensive skb_unclone() in iptunnel_handle_offloads() 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c0ef079c

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;