[PATCH 2/3] skb: Drop "fastpath" variable for skb_cloned check in pskb_expand_head
From: Alexander Duyck <hidden>
Date: 2012-05-05 00:26:36
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Since there is now only one spot that actually uses "fastpath" there isn't much point in carrying it. Instead we can just use a check for skb_cloned to verify if we can perform the fast-path free for the head or not. Signed-off-by: Alexander Duyck <redacted> --- net/core/skbuff.c | 22 ++++++++-------------- 1 files changed, 8 insertions(+), 14 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4d085d4..17e4b1e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -932,7 +932,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, u8 *data; int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail; long off; - bool fastpath; BUG_ON(nhead < 0);
@@ -941,16 +940,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, size = SKB_DATA_ALIGN(size); - /* Check if we can avoid taking references on fragments if we own - * the last reference on skb->head. (see skb_release_data()) - */ - if (!skb->cloned) - fastpath = true; - else { - int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1; - fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta; - } - data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), gfp_mask); if (!data)
@@ -966,9 +955,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, skb_shinfo(skb), offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags])); - if (fastpath) { - skb_free_head(skb); - } else { + /* + * if shinfo is shared we must drop the old head gracefully, but if it + * is not we can just drop the old head and let the existing refcount + * be since all we did is relocate the values + */ + if (skb_cloned(skb)) { /* copy this zero copy skb frags */ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) { if (skb_copy_ubufs(skb, gfp_mask))
@@ -981,6 +973,8 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, skb_clone_fraglist(skb); skb_release_data(skb); + } else { + skb_free_head(skb); } off = (data + nhead) - skb->head;