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Date: Mon, 18 May 2020 15:55:02 +0200
From: Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v2 23/33] iommu/mediatek-v1 Convert to
 probe/release_device() call-backs
Message-ID: <20200518135502.GE18353@8bytes.org>
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To: Yong Wu <yong.wu@mediatek.com>
Cc: Joerg Roedel <jroedel@suse.de>, Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Matthias Brugger <matthias.bgg@gmail.com>, Robin Murphy <robin.murphy@arm.com>, Marek Szyprowski <m.szyprowski@samsung.com>

Hi,

On Mon, May 18, 2020 at 02:51:20PM +0800, Yong Wu wrote:
> below is my local patch. split "dma_attach" to attach_device and
> probe_finalize. About attach_device, Use the existed
> __iommu_attach_group instead. Then rename from the "dma_attach" to
> "probe_finalize" to do the probe_finalize job. And move it outside of
> the mutex_unlock.
> 
> I'm not sure if it is right. and of course I will test if you have any
> other solution. Thanks.
> 
> 
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1665,26 +1665,20 @@ static void probe_alloc_default_domain(struct
> bus_type *bus,
>  
>  }
>  
> -static int iommu_group_do_dma_attach(struct device *dev, void *data)
> +static int iommu_group_do_probe_finalize(struct device *dev, void
> *data)
>  {
>  	struct iommu_domain *domain = data;
> -	const struct iommu_ops *ops;
> -	int ret;
> -
> -	ret = __iommu_attach_device(domain, dev);
> -
> -	ops = domain->ops;
> +	const struct iommu_ops *ops = domain->ops;
>  
> -	if (ret == 0 && ops->probe_finalize)
> +	if (ops->probe_finalize)
>  		ops->probe_finalize(dev);
> -
> -	return ret;
> +	return 0;
>  }
>  
> -static int __iommu_group_dma_attach(struct iommu_group *group)
> +static int iommu_group_probe_finalize(struct iommu_group *group)
>  {
>  	return __iommu_group_for_each_dev(group, group->default_domain,
> -					  iommu_group_do_dma_attach);
> +					  iommu_group_do_probe_finalize);
>  }
>  
>  static int iommu_do_create_direct_mappings(struct device *dev, void
> *data)
> @@ -1731,12 +1725,14 @@ int bus_iommu_probe(struct bus_type *bus)
>  
>  		iommu_group_create_direct_mappings(group);
>  
> -		ret = __iommu_group_dma_attach(group);
> +		ret = __iommu_attach_group(group->default_domain, group);
>  
>  		mutex_unlock(&group->mutex);
>  
>  		if (ret)
>  			break;
> +
> +		iommu_group_probe_finalize(group);
>  	}
>  
>  	return ret;
> -- 

Yes, I think moving the probe_finalize call out of the group->mutex
section is the right fix for this issue.

Thanks for reporting it and working on a fix.


Regards,

	Joerg