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Commit 20d5a540 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

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



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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 126e9be8

drivers/gpu/drm/i915/i915_debugfs.c

+0 −18
Original line number Diff line number Diff line
@@ -1956,16 +1956,11 @@ static int i915_forcewake_open(struct inode *inode, struct file *file) 
{

	struct drm_device *dev = inode->i_private;

	struct drm_i915_private *dev_priv = dev->dev_private;

	int ret;



	if (INTEL_INFO(dev)->gen < 6)

		return 0;



	ret = mutex_lock_interruptible(&dev->struct_mutex);

	if (ret)

		return ret;

	gen6_gt_force_wake_get(dev_priv);

	mutex_unlock(&dev->struct_mutex);



	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_i915_private *dev_priv = dev->dev_private;

	int ret;



	if (INTEL_INFO(dev)->gen < 6)

		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);

	mutex_unlock(&dev->struct_mutex);



	return 0;

}