Re: [PATCH v6 06/33] of/device: Move dma_range_map before of_iommu_configure

[Robin Murphy]

On 2021-01-15 05:30, Yong Wu wrote:
> On Thu, 2021-01-14 at 13:27 -0600, Rob Herring wrote:
> > On Mon, Jan 11, 2021 at 07:18:47PM +0800, Yong Wu wrote:
> > > "dev->dma_range_map" contains the devices' dma_ranges information,
> > > This patch moves dma_range_map before of_iommu_configure. The iommu
> > > driver may need to know the dma_address requirements of its iommu
> > > consumer devices.
> > >
> > > CC: Rob Herring <robh+dt@xxxxxxxxxx>
> > > CC: Frank Rowand <frowand.list@xxxxxxxxx>
> > > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > > ---
> > >   drivers/of/device.c | 3 ++-
> > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/of/device.c b/drivers/of/device.c
> > > index aedfaaafd3e7..1d84636149df 100644
> > > --- a/drivers/of/device.c
> > > +++ b/drivers/of/device.c
> > > @@ -170,9 +170,11 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
> > >   	dev_dbg(dev, "device is%sdma coherent\n",
> > >   		coherent ? " " : " not ");
> > >   
> > > +	dev->dma_range_map = map;
> > >   	iommu = of_iommu_configure(dev, np, id);
> > >   	if (PTR_ERR(iommu) == -EPROBE_DEFER) {
> > >   		kfree(map);
> > > +		dev->dma_range_map = NULL;
> >
> > Not really going to matter, but you should probably clear dma_range_map
> > before what it points to is freed.
> >
> > With that,
> >
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
>
> Thanks for the review. I will move it before "kfree(map)" in next
> version.

Paul noticed that we already have a bug in assigning to this 
unconditionally[1] - I'd totally forgotten about this series when I 
theorised about IOMMU drivers wanting the information earlier, but 
sweeping my inbox now only goes to show I was right to think of it :)

We should really get something in as a fix independent of this series, 
taking both angles into account.

Robin.

[1] 
https://lore.kernel.org/linux-arm-kernel/5c7946f3-b56e-da00-a750-be097c7ceb32@xxxxxxx/

> > >   		return -EPROBE_DEFER;
> > >   	}
> > >   
> > > @@ -181,7 +183,6 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
> > >   
> > >   	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
> > >   
> > > -	dev->dma_range_map = map;
> > >   	return 0;
> > >   }
> > >   EXPORT_SYMBOL_GPL(of_dma_configure_id);
> > > --
> > > 2.18.0
>
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