Re: [PATCH 3/9] drm/i915: Wrap drm_gem_object_lookup in i915_gem_object_lookup

[Dave Gordon <david.s.gordon@xxxxxxxxx>]

On 20/07/16 09:59, Chris Wilson wrote:
> For symmetry with a forthcoming i915_gem_object_get() and
> i915_gem_object_pu().
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/i915_drv.h        | 20 +++++++++++-
>   drivers/gpu/drm/i915/i915_gem.c        | 58 +++++++++++++++++-----------------
>   drivers/gpu/drm/i915/i915_gem_tiling.c |  8 ++---
>   drivers/gpu/drm/i915/intel_display.c   |  4 +--
>   drivers/gpu/drm/i915/intel_overlay.c   |  5 ++-
>   5 files changed, 56 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 2131e7f1e57a..47f244f9c64e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2286,7 +2286,25 @@ struct drm_i915_gem_object {
>   		} userptr;
>   	};
>   };
> -#define to_intel_bo(x) container_of(x, struct drm_i915_gem_object, base)
> +
> +static inline struct drm_i915_gem_object *
> +to_intel_bo(struct drm_gem_object *gem)
> +{
> +	/* Assert that to_intel_bo(NULL) == NULL */
> +	BUILD_BUG_ON(offsetof(struct drm_i915_gem_object, base));
> +
> +	return container_of(gem, struct drm_i915_gem_object, base);
> +}

Yes, I think this is a much better way of doing the conversion, 'cos 
it's type-safe and we get that all-important check that 'base' is still 
at offset 0.

In my variant on this, I also introduced the reverse mapping, 
to_gem_object(), so that we could completely abstract away the 
conversion back-and-forth between the two classes. Do you think that 
would be worth adding here too?

> +static inline struct drm_i915_gem_object *
> +i915_gem_object_lookup(struct drm_file *file, u32 handle)
> +{
> +	return to_intel_bo(drm_gem_object_lookup(file, handle));
> +}
> +
> +__deprecated
> +extern struct drm_gem_object *
> +drm_gem_object_lookup(struct drm_file *file, u32 handle);
>
>   static inline bool
>   i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index d825db7b763d..970496419098 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -864,8 +864,8 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {

Yes, this construct was not only bizarre, but could actually cause 
problems on some compilers. See
https://lists.freedesktop.org/archives/mesa-dev/2012-April/020514.html

Just writing 'obj' is much nicer :)

> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -1280,8 +1280,8 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		goto put_rpm;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -1497,8 +1497,8 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -1546,8 +1546,8 @@ i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -1587,7 +1587,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   		    struct drm_file *file)
>   {
>   	struct drm_i915_gem_mmap *args = data;
> -	struct drm_gem_object *obj;
> +	struct drm_i915_gem_object *obj;
>   	unsigned long addr;
>
>   	if (args->flags & ~(I915_MMAP_WC))
> @@ -1596,19 +1596,19 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   	if (args->flags & I915_MMAP_WC && !boot_cpu_has(X86_FEATURE_PAT))
>   		return -ENODEV;
>
> -	obj = drm_gem_object_lookup(file, args->handle);
> -	if (obj == NULL)
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj)
>   		return -ENOENT;
>
>   	/* prime objects have no backing filp to GEM mmap
>   	 * pages from.
>   	 */
> -	if (!obj->filp) {
> -		drm_gem_object_unreference_unlocked(obj);
> +	if (!obj->base.filp) {
> +		drm_gem_object_unreference_unlocked(&obj->base);
>   		return -EINVAL;
>   	}
>
> -	addr = vm_mmap(obj->filp, 0, args->size,
> +	addr = vm_mmap(obj->base.filp, 0, args->size,
>   		       PROT_READ | PROT_WRITE, MAP_SHARED,
>   		       args->offset);
>   	if (args->flags & I915_MMAP_WC) {
> @@ -1616,7 +1616,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   		struct vm_area_struct *vma;
>
>   		if (down_write_killable(&mm->mmap_sem)) {
> -			drm_gem_object_unreference_unlocked(obj);
> +			drm_gem_object_unreference_unlocked(&obj->base);
>   			return -EINTR;
>   		}
>   		vma = find_vma(mm, addr);
> @@ -1628,9 +1628,9 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   		up_write(&mm->mmap_sem);
>
>   		/* This may race, but that's ok, it only gets set */
> -		WRITE_ONCE(to_intel_bo(obj)->has_wc_mmap, true);
> +		WRITE_ONCE(obj->has_wc_mmap, true);
>   	}
> -	drm_gem_object_unreference_unlocked(obj);
> +	drm_gem_object_unreference_unlocked(&obj->base);
>   	if (IS_ERR((void *)addr))
>   		return addr;
>
> @@ -1968,8 +1968,8 @@ i915_gem_mmap_gtt(struct drm_file *file,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -2792,8 +2792,8 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->bo_handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->bo_handle);
> +	if (!obj) {
>   		mutex_unlock(&dev->struct_mutex);
>   		return -ENOENT;
>   	}
> @@ -3596,8 +3596,8 @@ int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
>   	struct drm_i915_gem_caching *args = data;
>   	struct drm_i915_gem_object *obj;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL)
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj)
>   		return -ENOENT;
>
>   	switch (obj->cache_level) {
> @@ -3657,8 +3657,8 @@ int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		goto rpm_put;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -4026,8 +4026,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> @@ -4091,8 +4091,8 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
>   	if (ret)
>   		return ret;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file_priv, args->handle));
> -	if (&obj->base == NULL) {
> +	obj = i915_gem_object_lookup(file_priv, args->handle);
> +	if (!obj) {
>   		ret = -ENOENT;
>   		goto unlock;
>   	}
> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> index 8030199731db..46e80f30afcd 100644
> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> @@ -166,8 +166,8 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
>   	struct drm_i915_gem_object *obj;
>   	int ret = 0;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL)
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj)
>   		return -ENOENT;
>
>   	if (!i915_tiling_ok(dev,
> @@ -297,8 +297,8 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
>   	struct drm_i915_private *dev_priv = to_i915(dev);
>   	struct drm_i915_gem_object *obj;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(file, args->handle));
> -	if (&obj->base == NULL)
> +	obj = i915_gem_object_lookup(file, args->handle);
> +	if (!obj)
>   		return -ENOENT;
>
>   	mutex_lock(&dev->struct_mutex);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 2f7af855a585..77d320584478 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -15089,8 +15089,8 @@ intel_user_framebuffer_create(struct drm_device *dev,
>   	struct drm_i915_gem_object *obj;
>   	struct drm_mode_fb_cmd2 mode_cmd = *user_mode_cmd;
>
> -	obj = to_intel_bo(drm_gem_object_lookup(filp, mode_cmd.handles[0]));
> -	if (&obj->base == NULL)
> +	obj = i915_gem_object_lookup(filp, mode_cmd.handles[0]);
> +	if (!obj)
>   		return ERR_PTR(-ENOENT);
>
>   	fb = intel_framebuffer_create(dev, &mode_cmd, obj);
> diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
> index 3212d8806b5a..5ca797b01ccb 100644
> --- a/drivers/gpu/drm/i915/intel_overlay.c
> +++ b/drivers/gpu/drm/i915/intel_overlay.c
> @@ -1122,9 +1122,8 @@ int intel_overlay_put_image_ioctl(struct drm_device *dev, void *data,
>   	}
>   	crtc = to_intel_crtc(drmmode_crtc);
>
> -	new_bo = to_intel_bo(drm_gem_object_lookup(file_priv,
> -						   put_image_rec->bo_handle));
> -	if (&new_bo->base == NULL) {
> +	new_bo = i915_gem_object_lookup(file_priv, put_image_rec->bo_handle);
> +	if (!new_bo) {
>   		ret = -ENOENT;
>   		goto out_free;
>   	}

LGTM.

Reviewed-by: Dave Gordon <david.s.gordon@xxxxxxxxx>

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