From be19f0ff482bd5f800d916683784a7e1474d5d6b Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 28 May 2014 16:16:42 +0100
Subject: [PATCH] drm/i915: Check for a NULL shared dpll before dereferencing
This doesn't look possible but a little extra defense against the
improbable is worth it - an oops here could lockup the machine.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/intel_display.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e7e95c3cf6ad..8635bb7878fe 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1760,6 +1760,9 @@ static void intel_prepare_shared_dpll(struct intel_crtc *crtc)
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_shared_dpll *pll = intel_crtc_to_shared_dpll(crtc);
+ if (WARN_ON(pll == NULL))
+ return;
+
WARN_ON(!pll->refcount);
if (pll->active == 0) {
DRM_DEBUG_DRIVER("setting up %s\n", pll->name);
--
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