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

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Message-ID: <20250625094013.GL1562@horms.kernel.org>
Date: Wed, 25 Jun 2025 10:40:13 +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 Wed, Jun 25, 2025 at 11:14:56AM +0200, Thomas Fourier wrote:
> On 24/06/2025 18:51, Simon Horman wrote:
> > 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.
> 
> 
> Hi Simon,
> 
> I don't see any reason why this would be a problem,
> 
> though, I don't think it is related and the change should be in the same
> patch.

Yes, good point. In that case this patch looks good to me.

Reviewed-by: Simon Horman <horms@...nel.org>

> Should I create another patch for that?

I think that would be nice. But let's wait for this patch to land first.