linux-kernel - Re: [PATCH net] net: mvneta: fix the remaining Rx descriptor unmapping issues

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Message-ID: <874leegb4p.fsf@bootlin.com>
Date:   Mon, 24 Sep 2018 17:37:10 +0200
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     Antoine Tenart <antoine.tenart@...tlin.com>
Cc:     davem@...emloft.net, yelena@...vell.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com,
        maxime.chevallier@...tlin.com, miquel.raynal@...tlin.com,
        nadavh@...vell.com, stefanc@...vell.com, ymarkman@...vell.com,
        mw@...ihalf.com
Subject: Re: [PATCH net] net: mvneta: fix the remaining Rx descriptor unmapping issues

Hi Antoine,
 
 On lun., sept. 24 2018, Antoine Tenart <antoine.tenart@...tlin.com> wrote:

> With CONFIG_DMA_API_DEBUG enabled we get DMA unmapping warning in
> various places of the mvneta driver, for example when putting down an
> interface while traffic is passing through.
>
> The issue is when using s/w buffer management, the Rx buffers are mapped
> using dma_map_page but unmapped with dma_unmap_single. This patch fixes
> this by using the right unmapping function.
>
> Fixes: 562e2f467e71 ("net: mvneta: Improve the buffer allocation method for SWBM")
> Signed-off-by: Antoine Tenart <antoine.tenart@...tlin.com>

Given the clarification provided by Yelen, this patch looks good:

Reviewed-by: Gregory CLEMENT <gregory.clement@...tlin.com>

Thanks,

Gregory


> ---
>  drivers/net/ethernet/marvell/mvneta.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 2db9708f2e24..b4ed7d394d07 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -1890,8 +1890,8 @@ static void mvneta_rxq_drop_pkts(struct mvneta_port *pp,
>  		if (!data || !(rx_desc->buf_phys_addr))
>  			continue;
>  
> -		dma_unmap_single(pp->dev->dev.parent, rx_desc->buf_phys_addr,
> -				 MVNETA_RX_BUF_SIZE(pp->pkt_size), DMA_FROM_DEVICE);
> +		dma_unmap_page(pp->dev->dev.parent, rx_desc->buf_phys_addr,
> +			       PAGE_SIZE, DMA_FROM_DEVICE);
>  		__free_page(data);
>  	}
>  }
> @@ -2039,9 +2039,8 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
>  						frag_offset, frag_size,
>  						PAGE_SIZE);
>  
> -				dma_unmap_single(dev->dev.parent, phys_addr,
> -						 PAGE_SIZE,
> -						 DMA_FROM_DEVICE);
> +				dma_unmap_page(dev->dev.parent, phys_addr,
> +					       PAGE_SIZE, DMA_FROM_DEVICE);
>  
>  				rxq->left_size -= frag_size;
>  			}
> -- 
> 2.17.1
>

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com