drm/i915: Assert that the kernel_context is hw-id 0

For easy recognisability, we want the kernel context to have id 0 and
all user contexts to have non-zero ids.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170123113132.18665-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 17f90c6182081c932652715ed34724f1c71b373d..77458da9627d4d1f80aa850185f07ad7f5f6a9a3 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -451,6 +451,11 @@ int i915_gem_context_init(struct drm_i915_private *dev_priv)
                return PTR_ERR(ctx);
        }
 
+       /* For easy recognisablity, we want the kernel context to be 0 and then
+        * all user contexts will have non-zero hw_id.
+        */
+       GEM_BUG_ON(ctx->hw_id);
+
        i915_gem_context_clear_bannable(ctx);
        ctx->priority = I915_PRIORITY_MIN; /* lowest priority; idle task */
        dev_priv->kernel_context = ctx;