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Date:   Mon, 1 Jul 2019 10:00:51 +0200
From:   Ludovic Desroches <ludovic.desroches@microchip.com>
To:     Raag Jadav <raagjadav@gmail.com>
CC:     <dmaengine@vger.kernel.org>, Vinod Koul <vkoul@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dmaengine: at_xdmac: check for non-empty xfers_list
 before invoking callback
Message-ID: <20190701080050.np5krtatlifnvtq5@M43218.corp.atmel.com>
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        dmaengine@vger.kernel.org, Vinod Koul <vkoul@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
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On Sat, Jun 29, 2019 at 01:50:48PM +0530, Raag Jadav wrote:
> 
> tx descriptor retrieved from an empty xfers_list may not have valid
> pointers to the callback functions.
> Avoid calling dmaengine_desc_get_callback_invoke if xfers_list is empty.
> 
> Signed-off-by: Raag Jadav <raagjadav@gmail.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Thanks

> ---
>  drivers/dma/at_xdmac.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index 627ef3e..b58ac72 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -1568,11 +1568,14 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
>  	struct at_xdmac_desc		*desc;
>  	struct dma_async_tx_descriptor	*txd;
>  
> -	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
> -	txd = &desc->tx_dma_desc;
> +	if (!list_empty(&atchan->xfers_list)) {
> +		desc = list_first_entry(&atchan->xfers_list,
> +					struct at_xdmac_desc, xfer_node);
> +		txd = &desc->tx_dma_desc;
>  
> -	if (txd->flags & DMA_PREP_INTERRUPT)
> -		dmaengine_desc_get_callback_invoke(txd, NULL);
> +		if (txd->flags & DMA_PREP_INTERRUPT)
> +			dmaengine_desc_get_callback_invoke(txd, NULL);
> +	}
>  }
>  
>  static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
> -- 
> 2.7.4
> 
>