[PATCH] i915: don't call drm_atomic_state_put on invalid pointer

* [PATCH] i915: don't call drm_atomic_state_put on invalid pointer
@ 2016-10-18 15:16 Arnd Bergmann
  2016-10-18 15:29   ` Eric Engestrom
  2016-10-18 15:56   ` Chris Wilson
  0 siblings, 2 replies; 7+ messages in thread
From: Arnd Bergmann @ 2016-10-18 15:16 UTC (permalink / raw)
  To: Daniel Vetter, Jani Nikula, David Airlie
  Cc: Arnd Bergmann, Chris Wilson, Daniel Vetter,
	Ville Syrjälä,
	Maarten Lankhorst, Imre Deak, Ander Conselvan de Oliveira,
	intel-gfx, dri-devel, linux-kernel

The introduction of reference counting on the state structures caused
sanitize_watermarks() in i915 to break in the error handling case,
as pointed out by gcc -Wmaybe-uninitialized

drivers/gpu/drm/i915/intel_display.c: In function ‘intel_modeset_init’:
include/drm/drm_atomic.h:224:2: error: ‘state’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the function back to only drop the reference count
when it was successfully allocated first.

Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/i915/intel_display.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 6d168685bbda..6a26da143aa6 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -16314,7 +16314,7 @@ static void sanitize_watermarks(struct drm_device *dev)
 		 * BIOS-programmed watermarks untouched and hope for the best.
 		 */
 		WARN(true, "Could not determine valid watermarks for inherited state\n");
-		goto fail;
+		goto put_state;
 	}
 
 	/* Write calculated watermark values back */
@@ -16325,8 +16325,9 @@ static void sanitize_watermarks(struct drm_device *dev)
 		dev_priv->display.optimize_watermarks(cs);
 	}
 
-fail:
+put_state:
 	drm_atomic_state_put(state);
+fail:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 }
-- 
2.9.0

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