On Fri, 2015-03-27 at 17:36 +0300, Dan Carpenter wrote:
> Hello Ander Conselvan de Oliveira,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 944b0c765757: "drm/i915: Copy the staged connector config
> to the legacy atomic state" from Mar 20, 2015, leads to the following
> Smatch complaint:
>
> drivers/gpu/drm/i915/intel_display.c:9118 intel_release_load_detect_pipe()
> error: we previously assumed 'state' could be null (see line 9082)
>
> drivers/gpu/drm/i915/intel_display.c
> 9081 state = drm_atomic_state_alloc(dev);
> 9082 if (!state)
> 9083 goto fail;
> ^^^^^^^^^
> Patch changes a return into a goto.
>
> 9084
> 9085 state->acquire_ctx = ctx;
> 9086
> 9087 connector_state =
> drm_atomic_get_connector_state(state, connector);
> 9088 if (IS_ERR(connector_state))
> 9089 goto fail;
> 9090
> 9091 to_intel_connector(connector)->new_encoder =
> NULL;
> 9092 intel_encoder->new_crtc = NULL;
> 9093 intel_crtc->new_enabled = false;
> 9094 intel_crtc->new_config = NULL;
> 9095
> 9096 connector_state->best_encoder = NULL;
> 9097 connector_state->crtc = NULL;
> 9098
> 9099 intel_set_mode(crtc, NULL, 0, 0, NULL, state);
> 9100
> 9101 drm_atomic_state_free(state);
> 9102
> 9103 if (old->release_fb) {
> 9104
> drm_framebuffer_unregister_private(old->release_fb);
> 9105
> drm_framebuffer_unreference(old->release_fb);
> 9106 }
> 9107
> 9108 return;
> 9109 }
> 9110
> 9111 /* Switch crtc and encoder back off if necessary */
> 9112 if (old->dpms_mode != DRM_MODE_DPMS_ON)
> 9113 connector->funcs->dpms(connector,
> old->dpms_mode);
> 9114
> 9115 return;
> 9116 fail:
> 9117 DRM_DEBUG_KMS("Couldn't release load detect pipe.\n");
> 9118 drm_atomic_state_free(state);
> ^^^^^
> Dereferenced inside function call.
That's odd, this is checking the "fail" label inside another function.
The change above was in intel_get_load_detect_pipe(), and this is in
intel_release_load_detect_pipe().
Anyway, the fail path in intel_get_load_detect_pipe() does check for
state being NULL before using it.
Cheers,
Ander
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