 @@ -1,14 +1,14 @@
-/*	$NetBSD: linux_reservation.c,v 1.5 2018/08/27 14:13:00 riastradh Exp $	*/
+/*	$NetBSD: linux_reservation.c,v 1.6 2018/08/27 14:13:46 riastradh Exp $	*/
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Taylor R. Campbell.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
 @@ -20,27 +20,27 @@
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_reservation.c,v 1.5 2018/08/27 14:13:00 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_reservation.c,v 1.6 2018/08/27 14:13:46 riastradh Exp $");
 #include <linux/fence.h>
 #include <linux/reservation.h>
 DEFINE_WW_CLASS(reservation_ww_class __cacheline_aligned);
 static struct reservation_object_list *
 objlist_tryalloc(uint32_t n)
+{
 	struct reservation_object_list *list;
 	list = kmem_alloc(offsetof(typeof(*list), shared[n]), KM_NOSLEEP);
 	if (list == NULL)
 @@ -401,63 +401,66 @@ reservation_object_add_shared_fence(stru
 				replace = list->shared[i];
 				list->shared[i] = fence;
 				break;
+			}
+		}
 		/* If we didn't find one, add it at the end.  */
 		if (i == list->shared_count)
 			list->shared[list->shared_count++] = fence;
 		/* Commit the update.  */
 		reservation_object_write_commit(robj, &ticket);
 	} else {
-		KASSERT(list->shared_count < prealloc->shared_max);
+		uint32_t shared_count = (list == NULL? 0 : list->shared_count);
 		KASSERT(shared_count < prealloc->shared_max);
 		/*
 		 * Copy the fences over, but replace if we find one
 		 * with the same context number.
 		 */
-		for (i = 0; i < list->shared_count; i++) {
+		for (i = 0; i < shared_count; i++) {
 			if (replace == NULL &&
 			    list->shared[i]->context == fence->context) {
 				replace = list->shared[i];
 				prealloc->shared[i] = fence;
 			} else {
 				prealloc->shared[i] = list->shared[i];
+			}
+		}
-		prealloc->shared_count = list->shared_count;
+		prealloc->shared_count = shared_count;
 		/* If we didn't find one, add it at the end.  */
 		if (replace == NULL)
 			prealloc->shared[prealloc->shared_count++] = fence;
 		/* Now ready to replace the list.  Begin an update.  */
 		reservation_object_write_begin(robj, &ticket);
 		/* Replace the list.  */
 		robj->robj_list = prealloc;
 		robj->robj_prealloc = NULL;
 		/* Commit the update.  */
 		reservation_object_write_commit(robj, &ticket);
 		/*
-		 * Free the old list when it is convenient.  (We are
+		 * If there is an old list, free it when convenient.
-		 * not in a position at this point to sleep waiting for
+		 * (We are not in a position at this point to sleep
-		 * activity on all CPUs.)
+		 * waiting for activity on all CPUs.)
 		 */
-		objlist_defer_free(list);
+		if (list != NULL)
 			objlist_defer_free(list);
+	}
 	/* Release a fence if we replaced it.  */
 	if (replace)
 		fence_put(replace);
+}
 int
 reservation_object_get_fences_rcu(struct reservation_object *robj,
     struct fence **fencep, unsigned *nsharedp, struct fence ***sharedp)
+{
 	struct reservation_object_list *list;
 	struct fence *fence;