linux-kernel - RE: [RFC 1/2] of: reserved_mem: check return value of_dma

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Date:   Mon, 27 Nov 2017 04:15:55 +0000
From:   Peng Fan <peng.fan@....com>
To:     "hch@....de" <hch@....de>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "frowand.list@...il.com" <frowand.list@...il.com>
CC:     "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "van.freenix@...il.com" <van.freenix@...il.com>
Subject: RE: [RFC 1/2] of: reserved_mem: check return value of_dma_configure



> -----Original Message-----
> From: Peng Fan
> Sent: Sunday, November 26, 2017 9:14 PM
> To: hch@....de; m.szyprowski@...sung.com; robin.murphy@....com;
> gregkh@...uxfoundation.org; robh+dt@...nel.org; frowand.list@...il.com
> Cc: iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org;
> devicetree@...r.kernel.org; van.freenix@...il.com; Peng Fan
> <peng.fan@....com>
> Subject: [RFC 1/2] of: reserved_mem: check return value of_dma_configure
> 
> In commit <7b07cbefb6>("iommu: of: Handle IOMMU lookup failure with
> deferred probing or error"), there is possibility that of_dma_configure may fail.
> So in of_reserved_mem_device_init_by_idx,
> also need to propagate the return value of_dma_configure to caller, when
> need to use reserved memory for a device which needs iommu.

Seems my understanding is wrong, with iommu enabled, reserved memory will not be used
for devices with memory-region. Please still help review RFC 2/2.

Thanks,
Peng.

> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/of/of_reserved_mem.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 22b75c82e377..61523819b50e 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -357,9 +357,12 @@ int of_reserved_mem_device_init_by_idx(struct
> device *dev,
>  		/* ensure that dma_ops is set for virtual devices
>  		 * using reserved memory
>  		 */
> -		of_dma_configure(dev, np);
> -
> -		dev_info(dev, "assigned reserved memory node %s\n", rmem-
> >name);
> +		ret = of_dma_configure(dev, np);
> +		if (ret)
> +			of_reserved_mem_device_release(dev);
> +		else
> +			dev_info(dev, "assigned reserved memory node %s\n",
> +				 rmem->name);
>  	} else {
>  		kfree(rd);
>  	}
> --
> 2.14.1