linux-kernel - Re: [PATCH 1/3] dmaengine: at_xdmac: remove BUG

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Date:   Tue, 5 Feb 2019 13:30:51 +0100
From:   Ludovic Desroches <ludovic.desroches@...rochip.com>
To:     Nicolas Ferre <nicolas.ferre@...rochip.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <dmaengine@...r.kernel.org>, "Vinod Koul" <vkoul@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] dmaengine: at_xdmac: remove BUG_ON macro in tasklet

On Tue, Feb 05, 2019 at 12:03:41PM +0100, Nicolas Ferre wrote:
> Even if this case shouldn't happen when controller is properly programmed,
> it's still better to avoid dumping a kernel Oops for this.
> As the sequence may happen only for debugging purposes, log the error and
> just finish the tasklet call.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@...rochip.com>

Thanks

> ---
>  drivers/dma/at_xdmac.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index fe69dccfa0c0..37a269420435 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -1606,7 +1606,11 @@ static void at_xdmac_tasklet(unsigned long data)
>  					struct at_xdmac_desc,
>  					xfer_node);
>  		dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
> -		BUG_ON(!desc->active_xfer);
> +		if (!desc->active_xfer) {
> +			dev_err(chan2dev(&atchan->chan), "Xfer not active: exiting");
> +			spin_unlock_bh(&atchan->lock);
> +			return;
> +		}
>  
>  		txd = &desc->tx_dma_desc;
>  
> -- 
> 2.17.1
>