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scatterlist: atomic sg_mapping_iter() no longer needs disabled IRQs 

SG mapping iterator w/ SG_MITER_ATOMIC set required IRQ disabled because
it originally used KM_BIO_SRC_IRQ to allow use from IRQ handlers.
kmap_atomic() has long been updated to handle stacking atomic mapping
requests on per-cpu basis and only requires not sleeping while mapped.

Update sg_mapping_iter such that atomic iterators only require disabling
preemption instead of disabling IRQ.

While at it, convert wte weird @ARG@ notations to @ARG in the comment of
sg_miter_start().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Tejun Heo 2012-10-04 17:13:28 -07:00 committed by Linus Torvalds
parent 17d7aac9a5
commit 8290e2d2dc
1 changed files with 8 additions and 8 deletions
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16
lib/scatterlist.c
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@ -404,14 +404,13 @@ EXPORT_SYMBOL(sg_miter_start);
* @miter: sg mapping iter to proceed
*
* Description:
* Proceeds @miter@ to the next mapping. @miter@ should have been
* started using sg_miter_start(). On successful return,
* @miter@->page, @miter@->addr and @miter@->length point to the
* current mapping.
* Proceeds @miter to the next mapping. @miter should have been started
* using sg_miter_start(). On successful return, @miter->page,
* @miter->addr and @miter->length point to the current mapping.
*
* Context:
* IRQ disabled if SG_MITER_ATOMIC. IRQ must stay disabled till
* @miter@ is stopped. May sleep if !SG_MITER_ATOMIC.
* Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
* till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
*
* Returns:
* true if @miter contains the next mapping. false if end of sg
@ -465,7 +464,8 @@ EXPORT_SYMBOL(sg_miter_next);
* resources (kmap) need to be released during iteration.
*
* Context:
* IRQ disabled if the SG_MITER_ATOMIC is set. Don't care otherwise.
* Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
* otherwise.
*/
void sg_miter_stop(struct sg_mapping_iter *miter)
{
@ -479,7 +479,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
flush_kernel_dcache_page(miter->page);
if (miter->__flags & SG_MITER_ATOMIC) {
WARN_ON(!irqs_disabled());
WARN_ON_ONCE(preemptible());
kunmap_atomic(miter->addr);
} else
kunmap(miter->page);