From: Dan Carpenter Subject: [patch] i915: take struct_mutex in i915_dma_cleanup() Date: Wed, 23 Jun 2010 13:19:55 +0200 Message-ID: <20100623111954.GA16433@bicker> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: David Airlie Cc: Eric Anholt , Jesse Barnes , Chris Wilson , Zhenyu Wang , nanhai.zou@intel.com, Benny Halevy , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org intel_cleanup_ring_buffer() calls drm_gem_object_unreference() (as opposed to drm_gem_object_unreference_unlocked()) so it needs to be called with "struct_mutex" held. If we don't hold the lock, it triggers a BUG_ON(!mutex_is_locked(&dev->struct_mutex)); I also audited the other places that call intel_cleanup_ring_buffer() and they all hold the lock so they're OK. This was introduced in: 8187a2b70e3 "drm/i915: introduce intel_ring_buffer structure (V2)" and it's a regression from v2.6.34. Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=16247 Signed-off-by: Dan Carpenter Reported-by: Benny Halevy Tested-by: Benny Halevy diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 59a2bf8..3325af1 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -128,9 +128,11 @@ static int i915_dma_cleanup(struct drm_device * dev) if (dev->irq_enabled) drm_irq_uninstall(dev); + mutex_lock(&dev->struct_mutex); intel_cleanup_ring_buffer(dev, &dev_priv->render_ring); if (HAS_BSD(dev)) intel_cleanup_ring_buffer(dev, &dev_priv->bsd_ring); + mutex_unlock(&dev->struct_mutex); /* Clear the HWS virtual address at teardown */ if (I915_NEED_GFX_HWS(dev))