Commit 8290e2d2 authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 17d7aac9

lib/scatterlist.c

+8 −8
Original line number Diff line number Diff line
@@ -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);

CRA Git | Maintained and supported by SUSTech CRA and CCSE