The patch titled
aio: remove spurious ring head index modulo info->nr
has been added to the -mm tree. Its filename is
aio-remove-spurious-ring-head-index-modulo-info-nr.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: aio: remove spurious ring head index modulo info->nr
From: "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Zach Brown <zach.brown@xxxxxxxxxx>
Cc: Suparna Bhattacharya <suparna@xxxxxxxxxx>
Cc: Benjamin LaHaise <bcrl@xxxxxxxxx>
Cc: Badari Pulavarty <pbadari@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/aio.c | 4 +--
fs/aio.c.orig | 54 +++++++++++++++++++++++-------------------------
2 files changed, 28 insertions(+), 30 deletions(-)
diff -puN fs/aio.c~aio-remove-spurious-ring-head-index-modulo-info-nr fs/aio.c
--- a/fs/aio.c~aio-remove-spurious-ring-head-index-modulo-info-nr
+++ a/fs/aio.c
@@ -1036,7 +1036,7 @@ 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);
@@ -1049,7 +1049,7 @@ 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;
diff -puN fs/aio.c.orig~aio-remove-spurious-ring-head-index-modulo-info-nr fs/aio.c.orig
--- a/fs/aio.c.orig~aio-remove-spurious-ring-head-index-modulo-info-nr
+++ a/fs/aio.c.orig
@@ -1172,42 +1172,40 @@ retry:
}
aio_init_wait(&wait);
+wait:
+ prepare_to_wait_exclusive(&ctx->wait, &wait.wait, TASK_INTERRUPTIBLE);
+ ret = aio_read_evt(ctx, &ent);
+ if (!ret) {
+ wait.nr_wait = min_nr - i;
+ schedule();
+ if (signal_pending(tsk))
+ ret = -EINTR;
+ }
+ finish_wait(&ctx->wait, &wait.wait);
+
+ if (ret < 0)
+ goto out_cleanup;
+
while (likely(i < nr)) {
- do {
- prepare_to_wait_exclusive(&ctx->wait, &wait.wait,
- TASK_INTERRUPTIBLE);
- ret = aio_read_evt(ctx, &ent);
- if (ret)
- break;
- if (min_nr <= i)
- break;
- ret = 0;
- if (to.timed_out) /* Only check after read evt */
- break;
- wait.nr_wait = min_nr - i;
- schedule();
- if (signal_pending(tsk)) {
- ret = -EINTR;
+ if (ret) {
+ if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
+ dprintk("aio: lost an event due to EFAULT.\n");
+ ret = -EFAULT;
break;
}
- /*ret = aio_read_evt(ctx, &ent);*/
- } while (1) ;
- finish_wait(&ctx->wait, &wait.wait);
-
- if (unlikely(ret <= 0))
- break;
+ event++;
+ i++;
+ }
- ret = -EFAULT;
- if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
- dprintk("aio: lost an event due to EFAULT.\n");
+ ret = aio_read_evt(ctx, &ent);
+ if (unlikely(!ret)) {
+ if (i < min_nr && !to.timed_out)
+ goto wait;
break;
}
-
- /* Good, event copied to userland, update counts. */
- event ++;
- i ++;
}
+out_cleanup:
if (timeout)
clear_timeout(&to);
out:
_
Patches currently in -mm which might be from kenneth.w.chen@xxxxxxxxx are
ia64-alignment-bug-in-ldscript.patch
aio-fix-buggy-put_ioctx-call-in-aio_complete-v2.patch
aio-add-per-task-aio-wait-event-condition.patch
aio-streamline-read-events-after-woken-up.patch
aio-remove-spurious-ring-head-index-modulo-info-nr.patch
aio-make-aio_ring_info-nr_pages-an-unsigned-int.patch
mm-only-sched-add-a-few-scheduler-event-counters.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
