linux-kernel - Re: [PATCH v2] atm: idt77252: Add missing `dma_map

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Message-ID: <20250624165128.GA1562@horms.kernel.org>
Date: Tue, 24 Jun 2025 17:51:28 +0100
From: Simon Horman <horms@...nel.org>
To: Thomas Fourier <fourier.thomas@...il.com>
Cc: Jakub Kicinski <kuba@...nel.org>, Chas Williams <3chas3@...il.com>,
	"moderated list:ATM" <linux-atm-general@...ts.sourceforge.net>,
	"open list:ATM" <netdev@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] atm: idt77252: Add missing `dma_map_error()`

On Tue, Jun 24, 2025 at 08:41:47AM +0200, Thomas Fourier wrote:
> The DMA map functions can fail and should be tested for errors.
> 
> Signed-off-by: Thomas Fourier <fourier.thomas@...il.com>
> ---
>  drivers/atm/idt77252.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c
> index 1206ab764ba9..f2e91b7d79f0 100644
> --- a/drivers/atm/idt77252.c
> +++ b/drivers/atm/idt77252.c
> @@ -852,6 +852,8 @@ queue_skb(struct idt77252_dev *card, struct vc_map *vc,
>  
>  	IDT77252_PRV_PADDR(skb) = dma_map_single(&card->pcidev->dev, skb->data,
>  						 skb->len, DMA_TO_DEVICE);
> +	if (dma_mapping_error(&card->pcidev->dev, IDT77252_PRV_PADDR(skb)))
> +		return -ENOMEM;
>  
>  	error = -EINVAL;
>  
> @@ -1857,6 +1859,8 @@ add_rx_skb(struct idt77252_dev *card, int queue,
>  		paddr = dma_map_single(&card->pcidev->dev, skb->data,
>  				       skb_end_pointer(skb) - skb->data,
>  				       DMA_FROM_DEVICE);
> +		if (dma_mapping_error(&card->pcidev->dev, paddr))
> +			goto outpoolrm;
>  		IDT77252_PRV_PADDR(skb) = paddr;
>  
>  		if (push_rx_skb(card, skb, queue)) {
> @@ -1871,6 +1875,7 @@ add_rx_skb(struct idt77252_dev *card, int queue,
>  	dma_unmap_single(&card->pcidev->dev, IDT77252_PRV_PADDR(skb),
>  			 skb_end_pointer(skb) - skb->data, DMA_FROM_DEVICE);
>  
> +outpoolrm:
>  	handle = IDT77252_PRV_POOL(skb);
>  	card->sbpool[POOL_QUEUE(handle)].skb[POOL_INDEX(handle)] = NULL;

Hi Thomas,

Can sb_pool_remove() be used here?
It seems to be the converse of sb_pool_add().
And safer than the code above.
But perhaps I'm missing something.