Messages in this thread Patch in this message | | | Date | Tue, 13 Jan 2009 16:37:05 -0800 (PST) | Subject | Re: [PATCH] tcp: splice as many packets as possible at once | From | David Miller <> |
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From: Evgeniy Polyakov <zbr@ioremap.net> Date: Wed, 14 Jan 2009 03:22:52 +0300
> On Tue, Jan 13, 2009 at 04:16:25PM -0800, David Miller (davem@davemloft.net) wrote: > > I wish there were some way we could make this code grab and release a > > reference to the SKB data area (I mean skb_shinfo(skb)->dataref) to > > accomplish it's goals. > > Ugh... Clone without cloninig, but by increasing the dataref. Getting > that splice only needs that skb to track the head of the original, this > may really work.
Here is something I scrambled together, it is largely based upon Jarek's patch:
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5110b35..05126da 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -70,12 +70,17 @@ static struct kmem_cache *skbuff_head_cache __read_mostly; static struct kmem_cache *skbuff_fclone_cache __read_mostly; +static void skb_release_data(struct sk_buff *skb); + static void sock_pipe_buf_release(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { struct sk_buff *skb = (struct sk_buff *) buf->private; - kfree_skb(skb); + if (skb) + skb_release_data(skb); + else + put_page(buf->page); } static void sock_pipe_buf_get(struct pipe_inode_info *pipe, @@ -83,7 +88,10 @@ static void sock_pipe_buf_get(struct pipe_inode_info *pipe, { struct sk_buff *skb = (struct sk_buff *) buf->private; - skb_get(skb); + if (skb) + atomic_inc(&skb_shinfo(skb)->dataref); + else + get_page(buf->page); } static int sock_pipe_buf_steal(struct pipe_inode_info *pipe, @@ -1336,7 +1344,10 @@ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i) { struct sk_buff *skb = (struct sk_buff *) spd->partial[i].private; - kfree_skb(skb); + if (skb) + skb_release_data(skb); + else + put_page(spd->pages[i]); } /* @@ -1344,7 +1355,7 @@ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i) */ static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page, unsigned int len, unsigned int offset, - struct sk_buff *skb) + struct sk_buff *skb, int linear) { if (unlikely(spd->nr_pages == PIPE_BUFFERS)) return 1; @@ -1352,8 +1363,15 @@ static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page, spd->pages[spd->nr_pages] = page; spd->partial[spd->nr_pages].len = len; spd->partial[spd->nr_pages].offset = offset; - spd->partial[spd->nr_pages].private = (unsigned long) skb_get(skb); + spd->partial[spd->nr_pages].private = + (unsigned long) (linear ? skb : NULL); spd->nr_pages++; + + if (linear) + atomic_inc(&skb_shinfo(skb)->dataref); + else + get_page(page); + return 0; } @@ -1369,7 +1387,7 @@ static inline void __segment_seek(struct page **page, unsigned int *poff, static inline int __splice_segment(struct page *page, unsigned int poff, unsigned int plen, unsigned int *off, unsigned int *len, struct sk_buff *skb, - struct splice_pipe_desc *spd) + struct splice_pipe_desc *spd, int linear) { if (!*len) return 1; @@ -1392,7 +1410,7 @@ static inline int __splice_segment(struct page *page, unsigned int poff, /* the linear region may spread across several pages */ flen = min_t(unsigned int, flen, PAGE_SIZE - poff); - if (spd_fill_page(spd, page, flen, poff, skb)) + if (spd_fill_page(spd, page, flen, poff, skb, linear)) return 1; __segment_seek(&page, &poff, &plen, flen); @@ -1419,7 +1437,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, if (__splice_segment(virt_to_page(skb->data), (unsigned long) skb->data & (PAGE_SIZE - 1), skb_headlen(skb), - offset, len, skb, spd)) + offset, len, skb, spd, 1)) return 1; /* @@ -1429,7 +1447,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, const skb_frag_t *f = &skb_shinfo(skb)->frags[seg]; if (__splice_segment(f->page, f->page_offset, f->size, - offset, len, skb, spd)) + offset, len, skb, spd, 0)) return 1; }
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