From 3ece782693c4b64d588dd217868558ab9a19bfe7 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Thu, 3 Aug 2017 16:29:38 -0400 Subject: sock: skb_copy_ubufs support for compound pages Refine skb_copy_ubufs to support compound pages. With upcoming TCP zerocopy sendmsg, such fragments may appear. The existing code replaces each page one for one. Splitting each compound page into an independent number of regular pages can result in exceeding limit MAX_SKB_FRAGS if data is not exactly page aligned. Instead, fill all destination pages but the last to PAGE_SIZE. Split the existing alloc + copy loop into separate stages: 1. compute bytelength and minimum number of pages to store this. 2. allocate 3. copy, filling each page except the last to PAGE_SIZE bytes 4. update skb frag array Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- include/linux/skbuff.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index be76082f48aa..2f64e2bbb592 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1796,13 +1796,18 @@ static inline unsigned int skb_headlen(const struct sk_buff *skb) return skb->len - skb->data_len; } -static inline unsigned int skb_pagelen(const struct sk_buff *skb) +static inline unsigned int __skb_pagelen(const struct sk_buff *skb) { unsigned int i, len = 0; for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--) len += skb_frag_size(&skb_shinfo(skb)->frags[i]); - return len + skb_headlen(skb); + return len; +} + +static inline unsigned int skb_pagelen(const struct sk_buff *skb) +{ + return skb_headlen(skb) + __skb_pagelen(skb); } /** -- cgit v1.2.3