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scatterlist: allow limited chaining without ARCH_HAS_SG_CHAIN 

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 <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2015-08-07 18:15:11 +02:00 committed by Jens Axboe
parent 0048b4837a
commit 10c95ed9aa
2 changed files with 0 additions and 8 deletions
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4
include/linux/scatterlist.h
View File

@ -161,10 +161,6 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
struct scatterlist *sgl)
{
#ifndef CONFIG_ARCH_HAS_SG_CHAIN
BUG();
#endif
/*
* offset and length are unused for chain entry. Clear them.
*/

4
lib/scatterlist.c
View File

@ -105,16 +105,12 @@ EXPORT_SYMBOL(sg_nents_for_len);
**/
struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
{
#ifndef CONFIG_ARCH_HAS_SG_CHAIN
struct scatterlist *ret = &sgl[nents - 1];
#else
struct scatterlist *sg, *ret = NULL;
unsigned int i;
for_each_sg(sgl, sg, nents, i)
ret = sg;
#endif
#ifdef CONFIG_DEBUG_SG
BUG_ON(sgl[0].sg_magic != SG_MAGIC);
BUG_ON(!sg_is_last(ret));