drm/i915/gt: Cancel a hung context if already closed

Use the restored ability to check if a context is closed to decide
whether or not to immediately ban the context from further execution
after a hang.

Fixes: be90e344 ("drm/i915/gt: Cancel banned contexts after GT reset")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200319170707.8262-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_reset.c

@@ -88,6 +88,11 @@ static bool mark_guilty(struct i915_request *rq)
 	bool banned;
 	int i;
 
+	if (intel_context_is_closed(rq->context)) {
+		intel_context_set_banned(rq->context);
+		return true;
+	}
+
 	rcu_read_lock();
 	ctx = rcu_dereference(rq->context->gem_context);
 	if (ctx && !kref_get_unless_zero(&ctx->ref))