[PATCH 0/2] scatterlist: clean up

[PATCH 0/2] scatterlist: clean up

[Gilad Ben-Yossef]

Ran into these two clean up / optimization opportunities while chasing
an unrelated bug.

Gilad Ben-Yossef (2):
  scatterlist: reorder compound boolean expression
  scatterlist: do not disable IRQs in sg_copy_buffer

 lib/scatterlist.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

-- 
2.1.4

[PATCH 1/2] scatterlist: reorder compound boolean expression

[Gilad Ben-Yossef]

Test the cheaper boolean expression with no side effects first.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
---
 lib/scatterlist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 004fc70..393920f 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -666,7 +666,7 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 
 	local_irq_save(flags);
 
-	while (sg_miter_next(&miter) && offset < buflen) {
+	while ((offset < buflen) && sg_miter_next(&miter)) {
 		unsigned int len;
 
 		len = min(miter.length, buflen - offset);
-- 
2.1.4

[PATCH 2/2] scatterlist: do not disable IRQs in sg_copy_buffer

[Gilad Ben-Yossef]

Commit 50bed2e2862a ("sg: disable interrupts inside sg_copy_buffer")
introduced disabling interrupts in sg_copy_buffer() since atomic uses of
miter required it due to use of kmap_atomic().

However, as commit 8290e2d2dcbf ("scatterlist: atomic sg_mapping_iter()
no longer needs disabled IRQs") acknowledges disabling interrupts is no
longer needed for calls to kmap_atomic() and therefore unneeded for miter
ops either, so remove it from sg_copy_buffer().

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
---
 lib/scatterlist.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 393920f..c6cf822 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -651,7 +651,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 {
 	unsigned int offset = 0;
 	struct sg_mapping_iter miter;
-	unsigned long flags;
 	unsigned int sg_flags = SG_MITER_ATOMIC;
 
 	if (to_buffer)
@@ -664,8 +663,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 	if (!sg_miter_skip(&miter, skip))
 		return false;
 
-	local_irq_save(flags);
-
 	while ((offset < buflen) && sg_miter_next(&miter)) {
 		unsigned int len;
 
@@ -681,7 +678,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 
 	sg_miter_stop(&miter);
 
-	local_irq_restore(flags);
 	return offset;
 }
 EXPORT_SYMBOL(sg_copy_buffer);
-- 
2.1.4