Commit 3a7c1ee4 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

skb: Add skb_head_is_locked helper function 



This patch adds support for a skb_head_is_locked helper function.  It is
meant to be used any time we are considering transferring the head from
skb->head to a paged frag.  If the head is locked it means we cannot remove
the head from the skb so it must be copied or we must take the skb as a
whole.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 715dc1f3

include/linux/skbuff.h

+14 −0
Original line number Diff line number Diff line
@@ -2566,5 +2566,19 @@ static inline bool skb_is_recycleable(const struct sk_buff *skb, int skb_size) 


	return true;

}



/**

 * skb_head_is_locked - Determine if the skb->head is locked down

 * @skb: skb to check

 *

 * The head on skbs build around a head frag can be removed if they are

 * not cloned.  This function returns true if the skb head is locked down

 * due to either being allocated via kmalloc, or by being a clone with

 * multiple references to the head.

 */

static inline bool skb_head_is_locked(const struct sk_buff *skb)

{

	return !skb->head_frag || skb_cloned(skb);

}

#endif	/* __KERNEL__ */

#endif	/* _LINUX_SKBUFF_H */

net/core/skbuff.c

+1 −2
Original line number Diff line number Diff line
@@ -1699,7 +1699,6 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, 
			      struct splice_pipe_desc *spd, struct sock *sk)

{

	int seg;

	bool head_is_locked = !skb->head_frag || skb_cloned(skb);



	/* map the linear part :

	 * If skb->head_frag is set, this 'linear' part is backed by a
@@ -1710,7 +1709,7 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe, 
			     (unsigned long) skb->data & (PAGE_SIZE - 1),

			     skb_headlen(skb),

			     offset, len, skb, spd,

			     head_is_locked,

			     skb_head_is_locked(skb),

			     sk, pipe))

		return true;

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -4568,7 +4568,7 @@ static bool tcp_try_coalesce(struct sock *sk, 
		    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)

			return false;



		if (!from->head_frag || skb_cloned(from))

		if (skb_head_is_locked(from))

			return false;



		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));

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