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Commit 131ea667 authored by Ian Campbell's avatar Ian Campbell Committed by David S. Miller
Browse files

net: add APIs for manipulating skb page fragments. 



The primary aim is to add skb_frag_(ref|unref) in order to remove the use of
bare get/put_page on SKB pages fragments and to isolate users from subsequent
changes to the skb_frag_t data structure.

Signed-off-by: default avatarIan Campbell <ian.campbell@citrix.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7ae9ed8d

include/linux/skbuff.h

+168 −2
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/rcupdate.h>

#include <linux/dmaengine.h>

#include <linux/hrtimer.h>

#include <linux/dma-mapping.h>



/* Don't change this without changing skb_csum_unnecessary! */

#define CHECKSUM_NONE 0
@@ -1129,7 +1130,20 @@ static inline int skb_pagelen(const struct sk_buff *skb) 
	return len + skb_headlen(skb);

}



static inline void skb_fill_page_desc(struct sk_buff *skb, int i,

/**

 * __skb_fill_page_desc - initialise a paged fragment in an skb

 * @skb: buffer containing fragment to be initialised

 * @i: paged fragment index to initialise

 * @page: the page to use for this fragment

 * @off: the offset to the data with @page

 * @size: the length of the data

 *

 * Initialises the @i'th fragment of @skb to point to &size bytes at

 * offset @off within @page.

 *

 * Does not take any additional reference on the fragment.

 */

static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,

					struct page *page, int off, int size)

{

	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
@@ -1137,6 +1151,26 @@ static inline void skb_fill_page_desc(struct sk_buff *skb, int i, 
	frag->page		  = page;

	frag->page_offset	  = off;

	frag->size		  = size;

}



/**

 * skb_fill_page_desc - initialise a paged fragment in an skb

 * @skb: buffer containing fragment to be initialised

 * @i: paged fragment index to initialise

 * @page: the page to use for this fragment

 * @off: the offset to the data with @page

 * @size: the length of the data

 *

 * As per __skb_fill_page_desc() -- initialises the @i'th fragment of

 * @skb to point to &size bytes at offset @off within @page. In

 * addition updates @skb such that @i is the last fragment.

 *

 * Does not take any additional reference on the fragment.

 */

static inline void skb_fill_page_desc(struct sk_buff *skb, int i,

				      struct page *page, int off, int size)

{

	__skb_fill_page_desc(skb, i, page, off, size);

	skb_shinfo(skb)->nr_frags = i + 1;

}
@@ -1630,6 +1664,138 @@ static inline void netdev_free_page(struct net_device *dev, struct page *page) 
	__free_page(page);

}



/**

 * skb_frag_page - retrieve the page refered to by a paged fragment

 * @frag: the paged fragment

 *

 * Returns the &struct page associated with @frag.

 */

static inline struct page *skb_frag_page(const skb_frag_t *frag)

{

	return frag->page;

}



/**

 * __skb_frag_ref - take an addition reference on a paged fragment.

 * @frag: the paged fragment

 *

 * Takes an additional reference on the paged fragment @frag.

 */

static inline void __skb_frag_ref(skb_frag_t *frag)

{

	get_page(skb_frag_page(frag));

}



/**

 * skb_frag_ref - take an addition reference on a paged fragment of an skb.

 * @skb: the buffer

 * @f: the fragment offset.

 *

 * Takes an additional reference on the @f'th paged fragment of @skb.

 */

static inline void skb_frag_ref(struct sk_buff *skb, int f)

{

	__skb_frag_ref(&skb_shinfo(skb)->frags[f]);

}



/**

 * __skb_frag_unref - release a reference on a paged fragment.

 * @frag: the paged fragment

 *

 * Releases a reference on the paged fragment @frag.

 */

static inline void __skb_frag_unref(skb_frag_t *frag)

{

	put_page(skb_frag_page(frag));

}



/**

 * skb_frag_unref - release a reference on a paged fragment of an skb.

 * @skb: the buffer

 * @f: the fragment offset

 *

 * Releases a reference on the @f'th paged fragment of @skb.

 */

static inline void skb_frag_unref(struct sk_buff *skb, int f)

{

	__skb_frag_unref(&skb_shinfo(skb)->frags[f]);

}



/**

 * skb_frag_address - gets the address of the data contained in a paged fragment

 * @frag: the paged fragment buffer

 *

 * Returns the address of the data within @frag. The page must already

 * be mapped.

 */

static inline void *skb_frag_address(const skb_frag_t *frag)

{

	return page_address(skb_frag_page(frag)) + frag->page_offset;

}



/**

 * skb_frag_address_safe - gets the address of the data contained in a paged fragment

 * @frag: the paged fragment buffer

 *

 * Returns the address of the data within @frag. Checks that the page

 * is mapped and returns %NULL otherwise.

 */

static inline void *skb_frag_address_safe(const skb_frag_t *frag)

{

	void *ptr = page_address(skb_frag_page(frag));

	if (unlikely(!ptr))

		return NULL;



	return ptr + frag->page_offset;

}



/**

 * __skb_frag_set_page - sets the page contained in a paged fragment

 * @frag: the paged fragment

 * @page: the page to set

 *

 * Sets the fragment @frag to contain @page.

 */

static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)

{

	frag->page = page;

	__skb_frag_ref(frag);

}



/**

 * skb_frag_set_page - sets the page contained in a paged fragment of an skb

 * @skb: the buffer

 * @f: the fragment offset

 * @page: the page to set

 *

 * Sets the @f'th fragment of @skb to contain @page.

 */

static inline void skb_frag_set_page(struct sk_buff *skb, int f,

				     struct page *page)

{

	__skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);

}



/**

 * skb_frag_dma_map - maps a paged fragment via the DMA API

 * @device: the device to map the fragment to

 * @frag: the paged fragment to map

 * @offset: the offset within the fragment (starting at the

 *          fragment's own offset)

 * @size: the number of bytes to map

 * @direction: the direction of the mapping (%PCI_DMA_*)

 *

 * Maps the page associated with @frag to @device.

 */

static inline dma_addr_t skb_frag_dma_map(struct device *dev,

					  const skb_frag_t *frag,

					  size_t offset, size_t size,

					  enum dma_data_direction dir)

{

	return dma_map_page(dev, skb_frag_page(frag),

			    frag->page_offset + offset, size, dir);

}



/**

 *	skb_clone_writable - is the header of a clone writable

 *	@skb: buffer to check