Re: [PATCH] tcp: splice as many packets as possible at once

Jarek Poplawski
2009-01-14T12:07:22Z

On Wed, Jan 14, 2009 at 09:54:54AM +0000, Jarek Poplawski wrote:
> On Wed, Jan 14, 2009 at 01:29:19AM -0800, David Miller wrote:
...
> > net: Fix data corruption when splicing from sockets.
> >
> > From: Jarek Poplawski <jarkao2@gmail.com>
...
> >
> > Signed-off-by: David S. Miller <davem@davemloft.net>
>
> You are very brave! I'd prefer to wait for at least minimal testing
> by Willy...

On the other hand, I can't waste your trust like this (plus I'm not
suicidal), so a little update:

Based on a review by Changli Gao <xiaosuo@gmail.com>:
http://lkml.org/lkml/2008/2/26/210

Foreseen-by: Changli Gao <xiaosuo@gmail.com>
Diagnosed-by: Willy Tarreau <w@1wt.eu>
Reported-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>

>
> Thanks,
> Jarek P.
>
> BTW, an skb parameter could be removed from spd_fill_page() to make it
> even faster...
>
> ...
> > 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;
> >
> > + if (linear) {
> > + page = linear_to_page(page, len, offset);
> > + if (!page)
> > + return 1;
> > + }
> > +
> > 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->nr_pages++;
> > + get_page(page);
> > +
> > return 0;
> > }
> >
> > @@ -1369,7 +1382,7 @@ 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 +1405,7 @@ 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 +1432,7 @@ 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 +1442,7 @@ 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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