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

Robin Murphy
2021-01-18T15:52:12Z

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@kernel.org>
>>> CC: Frank Rowand <frowand.list@gmail.com>
>>> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
>>> ---
>>> 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@kernel.org>
>
> 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@arm.com/

>>
>>> 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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