Re: [PATCH] Revert "drm/i915: Disallow pin ioctl completely for kms drivers"

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] Revert "drm/i915: Disallow pin ioctl completely	for kms drivers"
Date: Thu, 27 Nov 2014 15:56:38 +0200	[thread overview]
Message-ID: <87oars3fxl.fsf@intel.com> (raw)
In-Reply-To: <1416915776-20730-1-git-send-email-chris@chris-wilson.co.uk>

On Tue, 25 Nov 2014, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> This reverts commit c211a47c2c28562f8a3fff9e027be1a3ed9e154a.
>
> This causes an unwarranteed API break for existing and active userspace.

Ville had an interesting observation regarding the commit being
reverted: https://bugs.freedesktop.org/show_bug.cgi?id=86679#c9

BR,
Jani.

>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 90 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 90 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 614bc2bc16fe..4a1ca7abd7f9 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4252,6 +4252,96 @@ i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj)
>  }
>  
>  int
> +i915_gem_pin_ioctl(struct drm_device *dev, void *data,
> +		   struct drm_file *file)
> +{
> +	struct drm_i915_gem_pin *args = data;
> +	struct drm_i915_gem_object *obj;
> +	int ret;
> +
> +	ret = i915_mutex_lock_interruptible(dev);
> +	if (ret)
> +		return ret;
> +
> +	obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
> +	if (&obj->base == NULL) {
> +		ret = -ENOENT;
> +		goto unlock;
> +	}
> +
> +	if (obj->madv != I915_MADV_WILLNEED) {
> +		DRM_DEBUG("Attempting to pin a purgeable buffer\n");
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +
> +	if (obj->pin_filp != NULL && obj->pin_filp != file) {
> +		DRM_DEBUG("Already pinned in i915_gem_pin_ioctl(): %d\n",
> +			  args->handle);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	if (obj->user_pin_count == ULONG_MAX) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	if (obj->user_pin_count == 0) {
> +		ret = i915_gem_obj_ggtt_pin(obj, args->alignment, PIN_MAPPABLE);
> +		if (ret)
> +			goto out;
> +	}
> +
> +	obj->user_pin_count++;
> +	obj->pin_filp = file;
> +
> +	args->offset = i915_gem_obj_ggtt_offset(obj);
> +out:
> +	drm_gem_object_unreference(&obj->base);
> +unlock:
> +	mutex_unlock(&dev->struct_mutex);
> +	return ret;
> +}
> +
> +int
> +i915_gem_unpin_ioctl(struct drm_device *dev, void *data,
> +		     struct drm_file *file)
> +{
> +	struct drm_i915_gem_pin *args = data;
> +	struct drm_i915_gem_object *obj;
> +	int ret;
> +
> +	ret = i915_mutex_lock_interruptible(dev);
> +	if (ret)
> +		return ret;
> +
> +	obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
> +	if (&obj->base == NULL) {
> +		ret = -ENOENT;
> +		goto unlock;
> +	}
> +
> +	if (obj->pin_filp != file) {
> +		DRM_DEBUG("Not pinned by caller in i915_gem_pin_ioctl(): %d\n",
> +			  args->handle);
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +	obj->user_pin_count--;
> +	if (obj->user_pin_count == 0) {
> +		obj->pin_filp = NULL;
> +		i915_gem_object_ggtt_unpin(obj);
> +	}
> +
> +out:
> +	drm_gem_object_unreference(&obj->base);
> +unlock:
> +	mutex_unlock(&dev->struct_mutex);
> +	return ret;
> +}
> +
> +int
>  i915_gem_busy_ioctl(struct drm_device *dev, void *data,
>  		    struct drm_file *file)
>  {
> -- 
> 2.1.3
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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