drm/i915: Dirty hack to fix selftests locking inversion

Some i915 selftests still use i915_vma_lock() as inner lock, and
intel_context_create_request() intel_timeline->mutex as outer lock.
Fortunately for selftests this is not an issue, they should be fixed
but we can move ahead and cleanify lockdep now.

Signed-off-by: Maarten Lankhorst <[email protected]>
Reviewed-by: Thomas Hellström <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Joonas Lahtinen <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index c05ef213bdc2..671081b0e4d6 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -459,6 +459,18 @@ struct i915_request *intel_context_create_request(struct intel_context *ce)
 	rq = i915_request_create(ce);
 	intel_context_unpin(ce);
 
+	if (IS_ERR(rq))
+		return rq;
+
+	/*
+	 * timeline->mutex should be the inner lock, but is used as outer lock.
+	 * Hack around this to shut up lockdep in selftests..
+	 */
+	lockdep_unpin_lock(&ce->timeline->mutex, rq->cookie);
+	mutex_release(&ce->timeline->mutex.dep_map, _RET_IP_);
+	mutex_acquire(&ce->timeline->mutex.dep_map, SINGLE_DEPTH_NESTING, 0, _RET_IP_);
+	rq->cookie = lockdep_pin_lock(&ce->timeline->mutex);
+
 	return rq;
 }