Re: [PATCH] dmaengine: dw-axi-dmac: simplify allocation

[Frank Li <Frank.li@nxp.com>]

On Mon, Mar 30, 2026 at 02:11:28PM -0700, Rosen Penev wrote:

Subject should
"use kzalloc_flex() to simplify allocation"

> Use a flexible array member with kzalloc_flex to combine allocations.

function name need add (), kzalloc_flex()

Frank
>
> Add __counted_by for extra runtime analysis.
>
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 8 +-------
>  drivers/dma/dw-axi-dmac/dw-axi-dmac.h          | 4 ++--
>  2 files changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> index 4d53f077e9d2..d3ca202dc478 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -294,15 +294,10 @@ static struct axi_dma_desc *axi_desc_alloc(u32 num)
>  {
>  	struct axi_dma_desc *desc;
>
> -	desc = kzalloc_obj(*desc, GFP_NOWAIT);
> +	desc = kzalloc_flex(*desc, hw_desc, num, GFP_NOWAIT);
>  	if (!desc)
>  		return NULL;
>
> -	desc->hw_desc = kzalloc_objs(*desc->hw_desc, num, GFP_NOWAIT);
> -	if (!desc->hw_desc) {
> -		kfree(desc);
> -		return NULL;
> -	}
>  	desc->nr_hw_descs = num;
>
>  	return desc;
> @@ -339,7 +334,6 @@ static void axi_desc_put(struct axi_dma_desc *desc)
>  		dma_pool_free(chan->desc_pool, hw_desc->lli, hw_desc->llp);
>  	}
>
> -	kfree(desc->hw_desc);
>  	kfree(desc);
>  	atomic_sub(descs_put, &chan->descs_allocated);
>  	dev_vdbg(chan2dev(chan), "%s: %d descs put, %d still allocated\n",
> diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> index 67cc199e24d1..a04a4e03eb3d 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> @@ -98,14 +98,14 @@ struct axi_dma_hw_desc {
>  };
>
>  struct axi_dma_desc {
> -	struct axi_dma_hw_desc	*hw_desc;
> -
>  	struct virt_dma_desc		vd;
>  	struct axi_dma_chan		*chan;
>  	u32				completed_blocks;
>  	u32				length;
>  	u32				period_len;
>  	u32				nr_hw_descs;
> +
> +	struct axi_dma_hw_desc		hw_desc[] __counted_by(nr_hw_descs);
>  };
>
>  struct axi_dma_chan_config {
> --
> 2.53.0
>