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authorEric Dumazet <edumazet@google.com>2014-12-04 04:04:39 +0300
committerDavid S. Miller <davem@davemloft.net>2014-12-09 21:40:20 +0300
commit6ffe75eb53564953e75c051e1c28676e1e56f385 (patch)
treedf3ded93cb68f3e739d1c490e8377dfee2fc028a /include/linux/skbuff.h
parent395eea6ccf2b253f81b4718ffbcae67d36fe2e69 (diff)
downloadlinux-6ffe75eb53564953e75c051e1c28676e1e56f385.tar.xz
net: avoid two atomic operations in fast clones
Commit ce1a4ea3f125 ("net: avoid one atomic operation in skb_clone()") took the wrong way to save one atomic operation. It is actually possible to avoid two atomic operations, if we do not change skb->fclone values, and only rely on clone_ref content to signal if the clone is available or not. skb_clone() can simply use the fast clone if clone_ref is 1. kfree_skbmem() can avoid the atomic_dec_and_test() if clone_ref is 1. Note that because we usually free the clone before the original skb, this particular attempt is only done for the original skb to have better branch prediction. SKB_FCLONE_FREE is removed. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Chris Mason <clm@fb.com> Cc: Sabrina Dubroca <sd@queasysnail.net> Cc: Vijay Subramanian <subramanian.vijay@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/skbuff.h')
-rw-r--r--include/linux/skbuff.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d1e2575000b9..e9281b5b7f59 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -344,7 +344,6 @@ enum {
SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
SKB_FCLONE_ORIG, /* orig skb (from fclone_cache) */
SKB_FCLONE_CLONE, /* companion fclone skb (from fclone_cache) */
- SKB_FCLONE_FREE, /* this companion fclone skb is available */
};
enum {
@@ -818,7 +817,7 @@ static inline bool skb_fclone_busy(const struct sock *sk,
fclones = container_of(skb, struct sk_buff_fclones, skb1);
return skb->fclone == SKB_FCLONE_ORIG &&
- fclones->skb2.fclone == SKB_FCLONE_CLONE &&
+ atomic_read(&fclones->fclone_ref) > 1 &&
fclones->skb2.sk == sk;
}