From 3a7c1ee4ab89f9250b8f82656a7be0ae14aa3691 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Thu, 3 May 2012 01:09:42 +0000 Subject: 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: Alexander Duyck Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/skbuff.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 988fc49667b1..37f539129d89 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -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 */ -- cgit v1.2.3