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drm/i915: don't grab dev->struct_mutex for userspace forcewak

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Since forcewake is now protected by a spinlock, we don't need to grab
dev->struct_mutex any more. This way we can also get rid of a stale
comment, noticed by Ben Widawsky while reviewing some locking changes.

v2: Kill the unused variable ret, noticed by Fengguang Wu.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-08-09 22:33:58 +02:00
parent 126e9be816
commit 20d5a540e5
1 changed files with 0 additions and 18 deletions
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18
drivers/gpu/drm/i915/i915_debugfs.c
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@ -1956,16 +1956,11 @@ static int i915_forcewake_open(struct inode *inode, struct file *file)
{ {
struct drm_device *dev = inode->i_private; struct drm_device *dev = inode->i_private;
struct drm_i915_private *dev_priv = dev->dev_private; struct drm_i915_private *dev_priv = dev->dev_private;
int ret;
if (INTEL_INFO(dev)->gen < 6) if (INTEL_INFO(dev)->gen < 6)
return 0; return 0;
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
gen6_gt_force_wake_get(dev_priv); gen6_gt_force_wake_get(dev_priv);
mutex_unlock(&dev->struct_mutex);
return 0; return 0;
} }
@ -1974,24 +1969,11 @@ static int i915_forcewake_release(struct inode *inode, struct file *file)
{ {
struct drm_device *dev = inode->i_private; struct drm_device *dev = inode->i_private;
struct drm_i915_private *dev_priv = dev->dev_private; struct drm_i915_private *dev_priv = dev->dev_private;
int ret;
if (INTEL_INFO(dev)->gen < 6) if (INTEL_INFO(dev)->gen < 6)
return 0; return 0;
/*
* It's bad that we can potentially hang userspace if struct_mutex gets
* forever stuck. However, if we cannot acquire this lock it means that
* almost certainly the driver has hung, is not unload-able. Therefore
* hanging here is probably a minor inconvenience not to be seen my
* almost every user.
*/
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
gen6_gt_force_wake_put(dev_priv); gen6_gt_force_wake_put(dev_priv);
mutex_unlock(&dev->struct_mutex);
return 0; return 0;
} }