linux-kernel - RE: [PATCH][next] dmaengine: dw-axi-dmac: remove redundant null check on desc

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Date:   Thu, 4 Feb 2021 00:18:56 +0000
From:   "Sia, Jee Heng" <jee.heng.sia@...el.com>
To:     Colin King <colin.king@...onical.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        "Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>
CC:     "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH][next] dmaengine: dw-axi-dmac: remove redundant null check
 on desc

The code looks good to me. I have also verified it on Intel KeemBay platform.

Reviewed-by: Sia Jee Heng <jee.heng.sia@...el.com>
Tested-by: Sia Jee Heng <jee.heng.sia@...el.com>

Thanks
Regards
Jee Heng
> -----Original Message-----
> From: Colin King <colin.king@...onical.com>
> Sent: 03 February 2021 9:47 PM
> To: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>; Vinod Koul
> <vkoul@...nel.org>; Sia, Jee Heng <jee.heng.sia@...el.com>; Andy
> Shevchenko <andriy.shevchenko@...ux.intel.com>;
> dmaengine@...r.kernel.org
> Cc: kernel-janitors@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: [PATCH][next] dmaengine: dw-axi-dmac: remove redundant
> null check on desc
> 
> From: Colin Ian King <colin.king@...onical.com>
> 
> The pointer desc is being null checked twice, the second null check is
> redundant because desc has not been re-assigned between the checks.
> Remove the redundant second null check on desc.
> 
> Addresses-Coverity: ("Logically dead code")
> Fixes: ef6fb2d6f1ab ("dmaengine: dw-axi-dmac: simplify descriptor
> management")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 4 ----
>  1 file changed, 4 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 ac3d81b72a15..d9e4ac3edb4e 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -919,10 +919,6 @@ dma_chan_prep_dma_memcpy(struct
> dma_chan *dchan, dma_addr_t dst_adr,
>  		num++;
>  	}
> 
> -	/* Total len of src/dest sg == 0, so no descriptor were
> allocated */
> -	if (unlikely(!desc))
> -		return NULL;
> -
>  	/* Set end-of-link to the last link descriptor of list */
>  	set_desc_last(&desc->hw_desc[num - 1]);
>  	/* Managed transfer list */
> --
> 2.29.2