[PATCH AUTOSEL for 4.9 40/56] drm/i915: Assert no external observers when unwind a failed request alloc

[alexander . levin]

From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

[ Upstream commit 1618bdb89b5d8b47edf42d9c6ea96ecf001ad625 ]

Before we return the request back to the kmem_cache after a failed
i915_gem_request_alloc(), we should assert that it has not been added to
any global state tracking.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/20161125131718.20978-2-chris@xxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_gem_request.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 8832f8ec1583..71e284d7c640 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -455,6 +455,11 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	return req;
 
 err_ctx:
+	/* Make sure we didn't add ourselves to external state before freeing */
+	GEM_BUG_ON(!list_empty(&req->active_list));
+	GEM_BUG_ON(!list_empty(&req->priotree.signalers_list));
+	GEM_BUG_ON(!list_empty(&req->priotree.waiters_list));
+
 	i915_gem_context_put(ctx);
 err:
 	kmem_cache_free(dev_priv->requests, req);
-- 
2.11.0