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 <[email protected]> Cc: Maxim Levitsky <[email protected]> Cc: Alex Dubov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
iegor · Oct 5, 2012 · 8290e2d · 8290e2d
1 parent 17d7aac
commit 8290e2d
Showing 1 changed file with 8 additions and 8 deletions.
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
@@ -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);