[PATCH v3] drm/vmwgfx: Make sure bo's are unpinned before putting them back

[Roland Scheidegger]

The logic is all complex, but looks good to me.

Reviewed-by: Roland Scheidegger <sroland at vmware.com>

On 13.04.21 22:59, Zack Rusin wrote:
> During cotable resize we pin the backup buffer to make sure the
> trylock doesn't fail. We were never unpinning the backup buffer
> resulting in every subsequent cotable resize trying to release a
> pinned bo. After we copy the old backup to the new we can release
> the pin.
> Mob's are always pinned so we just have to make sure we unpin
> them before releasing them.
> 
> Cc: Martin Krastev <krastevm at vmware.com>
> Cc: Roland Scheidegger <sroland at vmware.com>
> Fixes: d1a73c641afd ("drm/vmwgfx: Make sure we unpin no longer needed buffers")
> Cc: dri-devel at lists.freedesktop.org
> Signed-off-by: Zack Rusin <zackr at vmware.com>
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c |  4 ++++
>  drivers/gpu/drm/vmwgfx/vmwgfx_drv.h     |  5 +----
>  drivers/gpu/drm/vmwgfx/vmwgfx_mob.c     | 18 ++++++++++++++----
>  3 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c
> index ba658fa9cf6c..183571c387b7 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c
> @@ -481,11 +481,15 @@ static int vmw_cotable_resize(struct vmw_resource *res, size_t new_size)
>  	vmw_bo_unreference(&old_buf);
>  	res->id = vcotbl->type;
>  
> +	/* Release the pin acquired in vmw_bo_init */
> +	ttm_bo_unpin(bo);
> +
>  	return 0;
>  
>  out_map_new:
>  	ttm_bo_kunmap(&old_map);
>  out_wait:
> +	ttm_bo_unpin(bo);
>  	ttm_bo_unreserve(bo);
>  	vmw_bo_unreference(&buf);
>  
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> index 8087a9013455..eb76a6b9ebca 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> @@ -1522,11 +1522,8 @@ static inline void vmw_bo_unreference(struct vmw_buffer_object **buf)
>  	struct vmw_buffer_object *tmp_buf = *buf;
>  
>  	*buf = NULL;
> -	if (tmp_buf != NULL) {
> -		if (tmp_buf->base.pin_count > 0)
> -			ttm_bo_unpin(&tmp_buf->base);
> +	if (tmp_buf != NULL)
>  		ttm_bo_put(&tmp_buf->base);
> -	}
>  }
>  
>  static inline struct vmw_buffer_object *
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
> index a0b53141dded..f2d625415458 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
> @@ -94,6 +94,16 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob,
>  			     struct vmw_piter data_iter,
>  			     unsigned long num_data_pages);
>  
> +
> +static inline void vmw_bo_unpin_unlocked(struct ttm_buffer_object *bo)
> +{
> +	int ret = ttm_bo_reserve(bo, false, true, NULL);
> +	BUG_ON(ret != 0);
> +	ttm_bo_unpin(bo);
> +	ttm_bo_unreserve(bo);
> +}
> +
> +
>  /*
>   * vmw_setup_otable_base - Issue an object table base setup command to
>   * the device
> @@ -277,7 +287,7 @@ static int vmw_otable_batch_setup(struct vmw_private *dev_priv,
>  						 &batch->otables[i]);
>  	}
>  
> -	ttm_bo_unpin(batch->otable_bo);
> +	vmw_bo_unpin_unlocked(batch->otable_bo);
>  	ttm_bo_put(batch->otable_bo);
>  	batch->otable_bo = NULL;
>  	return ret;
> @@ -341,9 +351,9 @@ static void vmw_otable_batch_takedown(struct vmw_private *dev_priv,
>  	BUG_ON(ret != 0);
>  
>  	vmw_bo_fence_single(bo, NULL);
> +	ttm_bo_unpin(bo);
>  	ttm_bo_unreserve(bo);
>  
> -	ttm_bo_unpin(batch->otable_bo);
>  	ttm_bo_put(batch->otable_bo);
>  	batch->otable_bo = NULL;
>  }
> @@ -530,7 +540,7 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob,
>  void vmw_mob_destroy(struct vmw_mob *mob)
>  {
>  	if (mob->pt_bo) {
> -		ttm_bo_unpin(mob->pt_bo);
> +		vmw_bo_unpin_unlocked(mob->pt_bo);
>  		ttm_bo_put(mob->pt_bo);
>  		mob->pt_bo = NULL;
>  	}
> @@ -646,7 +656,7 @@ int vmw_mob_bind(struct vmw_private *dev_priv,
>  out_no_cmd_space:
>  	vmw_fifo_resource_dec(dev_priv);
>  	if (pt_set_up) {
> -		ttm_bo_unpin(mob->pt_bo);
> +		vmw_bo_unpin_unlocked(mob->pt_bo);
>  		ttm_bo_put(mob->pt_bo);
>  		mob->pt_bo = NULL;
>  	}
>