linux-kernel - Re: [PATCH] drm/ttm: use swap macro in ttm_bo_handle_move

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Date:   Thu, 12 Jul 2018 19:37:50 -0700
From:   Sinclair Yeh <syeh@...are.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Christian Koenig <christian.koenig@....com>,
        Roger He <Hongbo.He@....com>, David Airlie <airlied@...ux.ie>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/ttm: use swap macro in ttm_bo_handle_move_mem

On Mon, Jul 09, 2018 at 10:24:47AM -0500, Gustavo A. R. Silva wrote:
> Make use of the swap macro and remove unnecessary variable *tmp_mem*.
> This makes the code easier to read and maintain. Also, reduces the
> stack usage.
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 5d8688e52..5142dcb 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -287,12 +287,9 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
>  
>  	if (ret) {
>  		if (bdev->driver->move_notify) {
> -			struct ttm_mem_reg tmp_mem = *mem;
> -			*mem = bo->mem;
> -			bo->mem = tmp_mem;
> +			swap(*mem, bo->mem);
>  			bdev->driver->move_notify(bo, false, mem);
> -			bo->mem = *mem;
> -			*mem = tmp_mem;
> +			swap(*mem, bo->mem);

This code assumes bo->mem is the same as tmp_mem after the call to
move_notify. Is this always true?



>  		}
>  
>  		goto out_err;
> -- 
> 2.7.4
> 
> _______________________________________________
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