Re: [PATCH] drm/i915: Prevent signals from interrupting close()

[Ben Widawsky <benjamin.widawsky@intel.com>]

On Wed, Apr 09, 2014 at 08:03:39AM +0100, Chris Wilson wrote:
> We neither report any unfinished operations during releasing GEM objects
> associated with the file, and even if we did, it is bad form to report
> -EINTR from a close().
> 
> The root cause of the bug that first showed itself during close is that
> we do not do proper live tracking of vma and contexts under full-ppgtt,
> but this is useful piece of defensive programming enforcing our
> userspace API contract.
> 
> Cc: Ben Widawsky <benjamin.widawsky@intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 24dd55a16436..d67ca8051e07 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1937,9 +1937,18 @@ void i915_driver_lastclose(struct drm_device * dev)
>  
>  void i915_driver_preclose(struct drm_device * dev, struct drm_file *file_priv)
>  {
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	bool was_interruptible;
> +
>  	mutex_lock(&dev->struct_mutex);
> +	was_interruptible = dev_priv->mm.interruptible;
> +	WARN_ON(!was_interruptible);
> +	dev_priv->mm.interruptible = false;
> +
>  	i915_gem_context_close(dev, file_priv);
>  	i915_gem_release(dev, file_priv);
> +
> +	dev_priv->mm.interruptible = was_interruptible;
>  	mutex_unlock(&dev->struct_mutex);
>  }
>  

I guess you missed:
1396905423-19453-1-git-send-email-benjamin.widawsky@intel.com

True in my case, I should have put the read of
'dev_priv->mm.interruptible' within the lock.

I don't think we need to protect gem_release.

-- 
Ben Widawsky, Intel Open Source Technology Center