linux-toradex.git/include/linux/scatterlist.h, branch v4.11-rc3

lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c

2016-04-15T20:53:14+00:00

Now it's ready to move the mempool based SG chained allocator code from
SCSI driver to lib/sg_pool.c, which will be compiled only based on a Kconfig
symbol CONFIG_SG_POOL.

SCSI selects CONFIG_SG_POOL.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Ming Lin 
Reviewed-by: Sagi Grimberg 
Signed-off-by: Martin K. Petersen

lib: scatterlist: add sg splitting function

2015-08-24T20:28:01+00:00

Sometimes a scatter-gather has to be split into several chunks, or sub
scatter lists. This happens for example if a scatter list will be
handled by multiple DMA channels, each one filling a part of it.

A concrete example comes with the media V4L2 API, where the scatter list
is allocated from userspace to hold an image, regardless of the
knowledge of how many DMAs will fill it :
 - in a simple RGB565 case, one DMA will pump data from the camera ISP
   to memory
 - in the trickier YUV422 case, 3 DMAs will pump data from the camera
   ISP pipes, one for pipe Y, one for pipe U and one for pipe V

For these cases, it is necessary to split the original scatter list into
multiple scatter lists, which is the purpose of this patch.

The guarantees that are required for this patch are :
 - the intersection of spans of any couple of resulting scatter lists is
   empty.
 - the union of spans of all resulting scatter lists is a subrange of
   the span of the original scatter list.
 - streaming DMA API operations (mapping, unmapping) should not happen
   both on both the resulting and the original scatter list. It's either
   the first or the later ones.
 - the caller is reponsible to call kfree() on the resulting
   scatterlists.

Signed-off-by: Robert Jarzmik 
Signed-off-by: Jens Axboe

scatterlist: allow limited chaining without ARCH_HAS_SG_CHAIN

2015-08-17T14:12:51+00:00

There are a couple of uses of struct scatterlist that never go to
the dma_map_sg() helper and thus don't care about ARCH_HAS_SG_CHAIN
which indicates that we can map chained S/G list.

The most important one is the crypto code, which currently has
to open code a few helpers to always allow chaining.  This patch
removes a few #ifdef ARCH_HAS_SG_CHAIN statements so that we can
switch the crypto code to these common helpers.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

drivers/scsi/scsi_debug.c: resolve sg buffer const-ness issue

2015-07-01T02:44:59+00:00

do_device_access() takes a separate parameter to indicate the direction of
data transfer, which it used to use to select the appropriate function out
of sg_pcopy_{to,from}_buffer().  However these two functions now have

So this patch makes it bypass these wrappers and call the underlying
function sg_copy_buffer() directly; this has the same calling style as
do_device_access() i.e.  a separate direction-of-transfer parameter and no
pointers-to-const, so skipping the wrappers not only eliminates the
warning, it also make the code simpler :)

[akpm@linux-foundation.org: fix very broken build]
Signed-off-by: Dave Gordon 
Acked-by: Arnd Bergmann 
Cc: James Bottomley 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: mark input buffer parameters as 'const'

2015-07-01T02:44:59+00:00

The 'buf' parameter of sg(p)copy_from_buffer() can and should be
const-qualified, although because of the shared implementation of
_to_buffer() and _from_buffer(), we have to cast this away internally.

This means that callers who have a 'const' buffer containing the data to
be copied to the sg-list no longer have to cast away the const-ness
themselves.  It also enables improved coverage by code analysis tools.

Signed-off-by: Dave Gordon 
Cc: Akinobu Mita 
Cc: "Martin K. Petersen" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-4.2/sg' of git://git.kernel.dk/linux-block

2015-06-25T22:22:36+00:00

Pull asm/scatterlist.h removal from Jens Axboe:
 "We don't have any specific arch scatterlist anymore, since parisc
  finally switched over.  Kill the include"

* 'for-4.2/sg' of git://git.kernel.dk/linux-block:
  remove scatterlist.h generation from arch Kbuild files
  remove

scatterlist: introduce sg_nents_for_len

2015-06-03T02:51:27+00:00

When performing a dma_map_sg() call, the number of sg entries to map is
required. Using sg_nents to retrieve the number of sg entries will
return the total number of entries in the sg list up to the entry marked
as the end. If there happen to be unused entries in the list, these will
still be counted. Some dma_map_sg() implementations will not handle the
unused entries correctly (lib/swiotlb.c) and execute a BUG_ON.

The sg_nents_for_len() function will traverse the sg list and return the
number of entries required to satisfy the supplied length argument. This
can then be supplied to the dma_map_sg() call to successfully map the
sg.

Signed-off-by: Tom Lendacky 
Signed-off-by: Herbert Xu

remove

2015-05-05T19:35:39+00:00

We don't have any arch specific scatterlist now that parisc switched over
to the generic one.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

lib/scatterlist: make ARCH_HAS_SG_CHAIN an actual Kconfig

2014-08-08T22:57:26+00:00

Rather than have architectures #define ARCH_HAS_SG_CHAIN in an
architecture specific scatterlist.h, make it a proper Kconfig option and
use that instead.  At same time, remove the header files are are now
mostly useless and just include asm-generic/scatterlist.h.

[sfr@canb.auug.org.au: powerpc files now need asm/dma.h]
Signed-off-by: Laura Abbott 
Acked-by: Thomas Gleixner 			[x86]
Acked-by: Benjamin Herrenschmidt 	[powerpc]
Acked-by: Heiko Carstens 
Cc: Russell King 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Paul Mackerras 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: "James E.J. Bottomley" 
Cc: Martin Schwidefsky 
Signed-off-by: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

scatterlist: allow chaining to preallocated chunks

2014-07-25T21:16:21+00:00

Blk-mq drivers usually preallocate their S/G list as part of the request,
but if we want to support the very large S/G lists currently supported by
the SCSI code that would tie up a lot of memory in the preallocated request
pool.  Add support to the scatterlist code so that it can initialize a
S/G list that uses a preallocated first chunks and dynamically allocated
additional chunks.  That way the scsi-mq code can preallocate a first
page worth of S/G entries as part of the request, and dynamically extend
the S/G list when needed.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Webb Scales 
Acked-by: Jens Axboe 
Tested-by: Bart Van Assche 
Tested-by: Robert Elliott