Re: [PATCH 10/36] drm/gem: add _locked suffix to drm_object_put

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, May 07, 2020 at 04:07:56PM +0100, Emil Velikov wrote:
> From: Emil Velikov <emil.velikov@collabora.com>
> 
> Vast majority of DRM (core and drivers) are struct_mutex free.
> 
> As such we have only a handful of cases where the locked helper should
> be used. Make that stand out a little bit better.
> 
> Done via the following script:
> 
> __from=drm_gem_object_put
> __to=drm_gem_object_put_locked
> 
> for __file in $(git grep --name-only --word-regexp $__from); do
>   sed -i  "s/\<$__from\>/$__to/g" $__file;
> done
> 
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: Sean Paul <sean@poorly.run>
> Cc: linux-arm-msm@vger.kernel.org
> Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

Since

commit 48e7f18392c66f9b69ebac11c54f1a2e033ced54
Author: Kristian H. Kristensen <hoegsberg@gmail.com>
Date:   Wed Mar 20 10:09:08 2019 -0700

    drm/msm: Implement .gem_free_object_unlocked

msm doesn't need the struct_mutex in the bo_put anymore, the only reason
we had to use the _locked version here is historical accidents I think.

I think you could convert these all to the _unlocked variant and then
entirely drop the _locked version.

Once we have that we could move struct_mutex into each driver (at least
for msm and i915) since it's purely internal, and then wrap it in an
#ifdef CONFIG_DRM_LEGACY to gloriously sunset it all :-)

Cheers, Daniel

> ---
>  drivers/gpu/drm/drm_gem.c                 | 6 +++---
>  drivers/gpu/drm/msm/adreno/a5xx_debugfs.c | 4 ++--
>  drivers/gpu/drm/msm/msm_drv.c             | 2 +-
>  drivers/gpu/drm/msm/msm_gem.c             | 6 +++---
>  drivers/gpu/drm/msm/msm_gem_submit.c      | 2 +-
>  drivers/gpu/drm/msm/msm_gpu.c             | 2 +-
>  include/drm/drm_gem.h                     | 4 ++--
>  7 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 599d5ff53b73..f21327ebc562 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -983,7 +983,7 @@ drm_gem_object_free(struct kref *kref)
>  EXPORT_SYMBOL(drm_gem_object_free);
>  
>  /**
> - * drm_gem_object_put - release a GEM buffer object reference
> + * drm_gem_object_put_locked - release a GEM buffer object reference
>   * @obj: GEM buffer object
>   *
>   * This releases a reference to @obj. Callers must hold the
> @@ -994,7 +994,7 @@ EXPORT_SYMBOL(drm_gem_object_free);
>   * drm_gem_object_put_unlocked() instead.
>   */
>  void
> -drm_gem_object_put(struct drm_gem_object *obj)
> +drm_gem_object_put_locked(struct drm_gem_object *obj)
>  {
>  	if (obj) {
>  		WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
> @@ -1002,7 +1002,7 @@ drm_gem_object_put(struct drm_gem_object *obj)
>  		kref_put(&obj->refcount, drm_gem_object_free);
>  	}
>  }
> -EXPORT_SYMBOL(drm_gem_object_put);
> +EXPORT_SYMBOL(drm_gem_object_put_locked);
>  
>  /**
>   * drm_gem_vm_open - vma->ops->open implementation for GEM
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c b/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c
> index 8cae2ca4af6b..68eddac7771c 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c
> @@ -124,13 +124,13 @@ reset_set(void *data, u64 val)
>  
>  	if (a5xx_gpu->pm4_bo) {
>  		msm_gem_unpin_iova(a5xx_gpu->pm4_bo, gpu->aspace);
> -		drm_gem_object_put(a5xx_gpu->pm4_bo);
> +		drm_gem_object_put_locked(a5xx_gpu->pm4_bo);
>  		a5xx_gpu->pm4_bo = NULL;
>  	}
>  
>  	if (a5xx_gpu->pfp_bo) {
>  		msm_gem_unpin_iova(a5xx_gpu->pfp_bo, gpu->aspace);
> -		drm_gem_object_put(a5xx_gpu->pfp_bo);
> +		drm_gem_object_put_locked(a5xx_gpu->pfp_bo);
>  		a5xx_gpu->pfp_bo = NULL;
>  	}
>  
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 29295dee2a2e..6baed5b43ea3 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -932,7 +932,7 @@ static int msm_ioctl_gem_madvise(struct drm_device *dev, void *data,
>  		ret = 0;
>  	}
>  
> -	drm_gem_object_put(obj);
> +	drm_gem_object_put_locked(obj);
>  
>  unlock:
>  	mutex_unlock(&dev->struct_mutex);
> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
> index 5a6a79fbc9d6..8696c405f709 100644
> --- a/drivers/gpu/drm/msm/msm_gem.c
> +++ b/drivers/gpu/drm/msm/msm_gem.c
> @@ -879,7 +879,7 @@ void msm_gem_describe_objects(struct list_head *list, struct seq_file *m)
>  }
>  #endif
>  
> -/* don't call directly!  Use drm_gem_object_put() and friends */
> +/* don't call directly!  Use drm_gem_object_put_locked() and friends */
>  void msm_gem_free_object(struct drm_gem_object *obj)
>  {
>  	struct msm_gem_object *msm_obj = to_msm_bo(obj);
> @@ -1183,7 +1183,7 @@ static void *_msm_gem_kernel_new(struct drm_device *dev, uint32_t size,
>  	return vaddr;
>  err:
>  	if (locked)
> -		drm_gem_object_put(obj);
> +		drm_gem_object_put_locked(obj);
>  	else
>  		drm_gem_object_put_unlocked(obj);
>  
> @@ -1215,7 +1215,7 @@ void msm_gem_kernel_put(struct drm_gem_object *bo,
>  	msm_gem_unpin_iova(bo, aspace);
>  
>  	if (locked)
> -		drm_gem_object_put(bo);
> +		drm_gem_object_put_locked(bo);
>  	else
>  		drm_gem_object_put_unlocked(bo);
>  }
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 385d4965a8d0..8f450a245cfb 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -387,7 +387,7 @@ static void submit_cleanup(struct msm_gem_submit *submit)
>  		struct msm_gem_object *msm_obj = submit->bos[i].obj;
>  		submit_unlock_unpin_bo(submit, i, false);
>  		list_del_init(&msm_obj->submit_entry);
> -		drm_gem_object_put(&msm_obj->base);
> +		drm_gem_object_put_locked(&msm_obj->base);
>  	}
>  }
>  
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index 615c5cda5389..86a68f96c48d 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -694,7 +694,7 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
>  		/* move to inactive: */
>  		msm_gem_move_to_inactive(&msm_obj->base);
>  		msm_gem_unpin_iova(&msm_obj->base, submit->aspace);
> -		drm_gem_object_put(&msm_obj->base);
> +		drm_gem_object_put_locked(&msm_obj->base);
>  	}
>  
>  	pm_runtime_mark_last_busy(&gpu->pdev->dev);
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 7c877bea7b3a..0f22f3320dcb 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -187,7 +187,7 @@ struct drm_gem_object {
>  	 *
>  	 * Reference count of this object
>  	 *
> -	 * Please use drm_gem_object_get() to acquire and drm_gem_object_put()
> +	 * Please use drm_gem_object_get() to acquire and drm_gem_object_put_locked()
>  	 * or drm_gem_object_put_unlocked() to release a reference to a GEM
>  	 * buffer object.
>  	 */
> @@ -376,7 +376,7 @@ drm_gem_object_put_unlocked(struct drm_gem_object *obj)
>  	kref_put(&obj->refcount, drm_gem_object_free);
>  }
>  
> -void drm_gem_object_put(struct drm_gem_object *obj);
> +void drm_gem_object_put_locked(struct drm_gem_object *obj);
>  
>  int drm_gem_handle_create(struct drm_file *file_priv,
>  			  struct drm_gem_object *obj,
> -- 
> 2.25.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch