drivers/block/as-iosched.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff -puN drivers/block/as-iosched.c~as-nr_dispatched-atomic-fix drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~as-nr_dispatched-atomic-fix	2003-03-07 12:24:24.000000000 -0800
+++ 25-akpm/drivers/block/as-iosched.c	2003-03-07 12:34:15.000000000 -0800
@@ -88,6 +88,9 @@ static unsigned long antic_expire = HZ /
 /*
  * This is the per-process anticipatory I/O scheduler state.  It is refcounted
  * and kmalloc'ed.
+ *
+ * There is no locking protecting the contents of this structure!  Pointers
+ * to a single as_io_context may appear in multiple queues at once.
  */
 
 struct as_io_context {
@@ -95,7 +98,7 @@ struct as_io_context {
 	pid_t pid;
 	unsigned long state;
 	atomic_t nr_queued; /* queued reads & sync writes */
-	unsigned long nr_dispatched; /* number of requests gone to the driver */
+	atomic_t nr_dispatched; /* number of requests gone to the drivers */
 };
 
 /* Bits in as_io_context.state */
@@ -239,7 +242,7 @@ static struct as_io_context *get_as_io_c
 			ret->pid = tsk->pid;
 			ret->state = 1 << AS_TASK_RUNNING;
 			atomic_set(&ret->nr_queued, 0);
-			ret->nr_dispatched = 0;
+			atomic_set(&ret->nr_dispatched, 0);
 			tsk->as_io_context = ret;
 		}
 	}
@@ -582,8 +585,8 @@ static void as_remove_dispatched_request
 		BUG_ON(arq->state != AS_RQ_DISPATCHED);
 		BUG_ON(ON_RB(&arq->rb_node));
 		if (arq->as_io_context) {
-			BUG_ON(arq->as_io_context->nr_dispatched == 0);
-			arq->as_io_context->nr_dispatched--;
+			BUG_ON(!atomic_read(&arq->as_io_context->nr_dispatched));
+			atomic_dec(&arq->as_io_context->nr_dispatched);
 		}
 		as_complete_arq(ad, arq);
 	}
@@ -751,7 +754,7 @@ static void as_move_to_dispatch(struct a
 	as_remove_queued_request(ad->q, arq->request);
 	list_add_tail(&arq->request->queuelist, ad->dispatch);
 	if (arq->as_io_context) 
-		arq->as_io_context->nr_dispatched++;
+		atomic_inc(&arq->as_io_context->nr_dispatched);
 
 	BUG_ON(arq->state != AS_RQ_QUEUED);
 	arq->state = AS_RQ_DISPATCHED;

_