From 72b5fd0199d6363e9556b03e591306354654d03e Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 17 Jan 2020 11:06:02 +0000
Subject: drm/i915: Satisfy smatch that a loop has at least one iteration
Git-commit: 416d3838f76b719cb47f076df73691eeac59a6ea
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Smatch worries that the engine->mask may be 0 leading to the loop being
shortcircuited leaving the next pointer unset,

drivers/gpu/drm/i915/i915_active.c:667 i915_active_acquire_preallocate_barrier() error: uninitialized symbol 'next'.

Assert that mask is not 0 and smatch can then verify that next must be
initialised before use.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200117110603.2982286-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/i915_active.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index b0a499753526..3d2e7cf55e52 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -623,6 +623,7 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 	 * We can then use the preallocated nodes in
 	 * i915_active_acquire_barrier()
 	 */
+	GEM_BUG_ON(!mask);
 	for_each_engine_masked(engine, gt, mask, tmp) {
 		u64 idx = engine->kernel_context->timeline->fence_context;
 		struct llist_node *prev = first;
-- 
2.28.0