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Subject[patch] aio: remove spurious ring head index modulo info->nr
Date
In aio_read_evt(), the ring->head will never wrap info->nr because
we already does the wrap when updating the ring head index:

if (head != ring->tail) {
...
head = (head + 1) % info->nr;
ring->head = head;
}
This makes the modulo of ring->head into local variable head unnecessary.
This patch removes that bogus code.


Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>


--- ./fs/aio.c.orig 2006-12-24 22:01:36.000000000 -0800
+++ ./fs/aio.c 2006-12-24 22:34:48.000000000 -0800
@@ -1019,7 +1019,7 @@ static int aio_read_evt(struct kioctx *i
{
struct aio_ring_info *info = &ioctx->ring_info;
struct aio_ring *ring;
- unsigned long head;
+ unsigned int head;
int ret = 0;

ring = kmap_atomic(info->ring_pages[0], KM_USER0);
@@ -1032,7 +1032,7 @@ static int aio_read_evt(struct kioctx *i

spin_lock(&info->ring_lock);

- head = ring->head % info->nr;
+ head = ring->head;
if (head != ring->tail) {
struct io_event *evp = aio_ring_event(info, head, KM_USER1);
*ent = *evp;
-
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