From 8290e2d2dcbf0d379d4b1379e17916515ee20a39 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 4 Oct 2012 17:13:28 -0700
Subject: [PATCH] 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>
---
lib/scatterlist.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index fadae774a20c..e76d85cf3175 100644
--- 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);