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

[Yong Wu]

On Mon, 2021-01-18 at 15:49 +0000, Robin Murphy wrote:
> 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.

Thanks this info. Following your suggestion, Move this into the "if (!
ret)". Then it is like this:


--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -163,8 +163,10 @@ int of_dma_configure_id(struct device *dev, struct
device_node *np,
 	dev->coherent_dma_mask &= mask;
 	*dev->dma_mask &= mask;
 	/* ...but only set bus limit if we found valid dma-ranges earlier */
-	if (!ret)
+	if (!ret) {
 		dev->bus_dma_limit = end;
+		dev->dma_range_map = map;
+	}
 
 	coherent = of_dma_is_coherent(np);
 	dev_dbg(dev, "device is%sdma coherent\n",
@@ -172,6 +174,8 @@ int of_dma_configure_id(struct device *dev, struct
device_node *np,
 
 	iommu = of_iommu_configure(dev, np, id);
 	if (PTR_ERR(iommu) == -EPROBE_DEFER) {
+		if (!ret)
+			dev->dma_range_map = NULL;
 		kfree(map);
 		return -EPROBE_DEFER;
 	}
@@ -181,7 +185,6 @@ 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);


If this is ok, I will send this as a independent patch.

> 
> 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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> >