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        Wed, 15 Apr 2020 02:10:21 -0400
Subject: Re: [PATCH v2 13/33] iommu: Export bus_iommu_probe() and make is safe
 for re-probing
References: <20200414131542.25608-1-joro@8bytes.org>
 <20200414131542.25608-14-joro@8bytes.org>
From: Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <1853992c-47a6-3724-812c-a52558c13732@linux.intel.com>
Date: Wed, 15 Apr 2020 14:10:03 +0800
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To: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com>, Marek Szyprowski <m.szyprowski@samsung.com>, Kukjin Kim <kgene@kernel.org>, Krzysztof Kozlowski <krzk@kernel.org>, David Woodhouse <dwmw2@infradead.org>, Andy Gross <agross@kernel.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, Matthias Brugger <matthias.bgg@gmail.com>, Rob Clark <robdclark@gmail.com>, Heiko Stuebner <heiko@sntech.de>, Gerald Schaefer <gerald.schaefer@de.ibm.com>, Thierry Reding <thierry.reding@gmail.com>, Jonathan Hunter <jonathanh@nvidia.com>, Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-s390@vger.kernel.org, linux-tegra@vger.kernel.org, virtualization@lists.linux-foundation.org, Joerg Roedel <jroedel@suse.de>

On 2020/4/14 21:15, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> Add a check to the bus_iommu_probe() call-path to make sure it ignores
> devices which have already been successfully probed. Then export the
> bus_iommu_probe() function so it can be used by IOMMU drivers.
> 
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>   drivers/iommu/iommu.c | 6 +++++-
>   include/linux/iommu.h | 1 +
>   2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 834a45da0ed0..a2ff95424044 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1615,6 +1615,10 @@ static int probe_iommu_group(struct device *dev, void *data)
>   	if (!dev_iommu_get(dev))
>   		return -ENOMEM;
>   
> +	/* Device is probed already if in a group */
> +	if (iommu_group_get(dev) != NULL)

Same as
	if (iommu_group_get(dev))
?

By the way, do we need to put the group if device has already been
probed?

Best regards,
baolu