1 files changed, 23 insertions, 19 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 12b37689dd2c..57b02791d04e 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -406,7 +406,8 @@ static void free_ioctx(struct work_struct *work)
         struct kioctx *ctx = container_of(work, struct kioctx, free_work);
         struct aio_ring *ring;
         struct kiocb *req;
-        unsigned cpu, head, avail;
+        unsigned cpu, avail;
+        DEFINE_WAIT(wait);
 
         spin_lock_irq(&ctx->ctx_lock);
 
@@ -427,22 +428,24 @@ static void free_ioctx(struct work_struct *work)
                 kcpu->reqs_available = 0;
         }
 
-        ring = kmap_atomic(ctx->ring_pages[0]);
-        head = ring->head;
-        kunmap_atomic(ring);
+        while (1) {
+                prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE);
 
-        while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) {
-                wait_event(ctx->wait,
-                           (head != ctx->tail) ||
-                           (atomic_read(&ctx->reqs_available) >=
-                            ctx->nr_events - 1));
-
-                avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
+                ring = kmap_atomic(ctx->ring_pages[0]);
+                avail = (ring->head <= ring->tail)
+                         ? ring->tail - ring->head
+                         : ctx->nr_events - ring->head + ring->tail;
 
                 atomic_add(avail, &ctx->reqs_available);
-                head += avail;
-                head %= ctx->nr_events;
+                ring->head = ring->tail;
+                kunmap_atomic(ring);
+
+                if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)
+                        break;
+
+                schedule();
         }
+        finish_wait(&ctx->wait, &wait);
 
         WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1);
 
@@ -869,7 +872,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
                                  struct io_event __user *event, long nr)
 {
         struct aio_ring *ring;
-        unsigned head, pos;
+        unsigned head, tail, pos;
         long ret = 0;
         int copy_ret;
 
@@ -877,11 +880,12 @@ static long aio_read_events_ring(struct kioctx *ctx,
 
         ring = kmap_atomic(ctx->ring_pages[0]);
         head = ring->head;
+        tail = ring->tail;
         kunmap_atomic(ring);
 
-        pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
+        pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
 
-        if (head == ctx->tail)
+        if (head == tail)
                 goto out;
 
         while (ret < nr) {
@@ -889,8 +893,8 @@ static long aio_read_events_ring(struct kioctx *ctx,
                 struct io_event *ev;
                 struct page *page;
 
-                avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
-                if (head == ctx->tail)
+                avail = (head <= tail ?  tail : ctx->nr_events) - head;
+                if (head == tail)
                         break;
 
                 avail = min(avail, nr - ret);
@@ -921,7 +925,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
         kunmap_atomic(ring);
         flush_dcache_page(ctx->ring_pages[0]);
 
-        pr_debug("%li  h%u t%u\n", ret, head, ctx->tail);
+        pr_debug("%li  h%u t%u\n", ret, head, tail);
 
         put_reqs_available(ctx, ret);
 out: