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Subject: Re: [PATCH 1/6] driver core: Introduce device_iommu_mapped() function
To:     Joerg Roedel <joro@8bytes.org>, iommu@lists.linux-foundation.org
Cc:     Russell Currey <ruscur@russell.cc>,
        Sam Bobroff <sbobroff@linux.ibm.com>, oohall@gmail.com,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Hanjun Guo <hanjun.guo@linaro.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Vinod Koul <vkoul@kernel.org>, jroedel@suse.de,
        Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        dmaengine@vger.kernel.org, linux-usb@vger.kernel.org
References: <20181211134343.10664-1-joro@8bytes.org>
 <20181211134343.10664-2-joro@8bytes.org>
From:   Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Organization: Cogent Embedded
Message-ID: <b1344a34-cd5f-f080-fddf-c1548f85af6a@cogentembedded.com>
Date:   Tue, 11 Dec 2018 17:59:33 +0300
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Hello!

On 12/11/2018 04:43 PM, Joerg Roedel wrote:

> From: Joerg Roedel <jroedel@suse.de>
> 
> Some places in the kernel check the iommu_group pointer in
> 'struct device' in order to find ot whether a device is
> mapped by an IOMMU.
> 
> This is not good way to make this check, as the pointer will
> be moved to 'struct dev_iommu_data'. This way to make the
> check is also not very readable.
> 
> Introduce an explicit function to perform this check.
> 
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Acked-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>  include/linux/device.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 1b25c7a43f4c..6cb4640b6160 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -1058,6 +1058,16 @@ static inline struct device *kobj_to_dev(struct kobject *kobj)
>  	return container_of(kobj, struct device, kobj);
>  }
>  
> +/**
> + * device_iommu_mapped - Returns true when the device DMA is translated
> + *			 by an IOMMU
> + * @dev: Device to perform the check on
> + */
> +static inline bool device_iommu_mapped(struct device *dev)
> +{
> +	return (dev->iommu_group != NULL);

   You know that parens are unnecessary here, right? :-)

> +}
> +
>  /* Get the wakeup routines, which depend on struct device */
>  #include <linux/pm_wakeup.h>
>  

MBR, Sergei