[Intel-gfx] [PATCH] drm/i915: Drop mutex around clearing error state

[David Weinehall]

On Thu, Sep 01, 2016 at 09:55:10PM +0100, Chris Wilson wrote:
> The error state itself is guarded by a spinlock (admittedly even that is
> overkill for a single pointer!) and doesn't require us to take the
> struct_mutex in the debugfs/sysfs interface. Removing the struct_mutex
> removes one more potential blockage when trying to debug a deadlock.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Lots of lines disappearing. Yay!

Reviewed-by: David Weinehall <david.weinehall at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 10 +---------
>  drivers/gpu/drm/i915/i915_sysfs.c   | 10 +---------
>  2 files changed, 2 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 7124e5666629..e238627c68b6 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -978,17 +978,9 @@ i915_error_state_write(struct file *filp,
>  		       loff_t *ppos)
>  {
>  	struct i915_error_state_file_priv *error_priv = filp->private_data;
> -	struct drm_device *dev = error_priv->dev;
> -	int ret;
>  
>  	DRM_DEBUG_DRIVER("Resetting error state\n");
> -
> -	ret = mutex_lock_interruptible(&dev->struct_mutex);
> -	if (ret)
> -		return ret;
> -
> -	i915_destroy_error_state(dev);
> -	mutex_unlock(&dev->struct_mutex);
> +	i915_destroy_error_state(error_priv->dev);
>  
>  	return cnt;
>  }
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index 2d482f677f56..1012eeea1324 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -556,17 +556,9 @@ static ssize_t error_state_write(struct file *file, struct kobject *kobj,
>  {
>  	struct device *kdev = kobj_to_dev(kobj);
>  	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
> -	struct drm_device *dev = &dev_priv->drm;
> -	int ret;
>  
>  	DRM_DEBUG_DRIVER("Resetting error state\n");
> -
> -	ret = mutex_lock_interruptible(&dev->struct_mutex);
> -	if (ret)
> -		return ret;
> -
> -	i915_destroy_error_state(dev);
> -	mutex_unlock(&dev->struct_mutex);
> +	i915_destroy_error_state(&dev_priv->drm);
>  
>  	return count;
>  }
> -- 
> 2.9.3
> 
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