linux-kernel - Re: [PATCH v12 3/4] iommu/arm-smmu: Add the device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5179668.PHK6S3sxLu@aspire.rjw.lan>
Date:   Wed, 11 Jul 2018 11:53:48 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     joro@...tes.org, robh+dt@...nel.org, mark.rutland@....com,
        robin.murphy@....com, will.deacon@....com,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        robdclark@...il.com, linux-pm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, sboyd@...nel.org,
        tfiga@...omium.org, sricharan@...eaurora.org,
        m.szyprowski@...sung.com, architt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, jcrouse@...eaurora.org,
        Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH v12 3/4] iommu/arm-smmu: Add the device_link between masters and smmu

On Sunday, July 8, 2018 7:34:12 PM CEST Vivek Gautam wrote:
> From: Sricharan R <sricharan@...eaurora.org>
> 
> Finally add the device link between the master device and
> smmu, so that the smmu gets runtime enabled/disabled only when the
> master needs it. This is done from add_device callback which gets
> called once when the master is added to the smmu.
> 
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
> Reviewed-by: Tomasz Figa <tfiga@...omium.org>
> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> Cc: Lukas Wunner <lukas@...ner.de>
> ---
> 
>  - Change since v11
>    * Replaced DL_FLAG_AUTOREMOVE flag with DL_FLAG_AUTOREMOVE_SUPPLIER.
> 
>  drivers/iommu/arm-smmu.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 09265e206e2d..916cde4954d2 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1461,8 +1461,20 @@ static int arm_smmu_add_device(struct device *dev)
>  
>  	iommu_device_link(&smmu->iommu, dev);
>  
> +	if (pm_runtime_enabled(smmu->dev) &&

Why does the creation of the link depend on whether or not runtime PM
is enabled for the MMU device?

What about system-wide PM and system shutdown?  Are they always guaranteed
to happen in the right order without the link?

> +	    !device_link_add(dev, smmu->dev,
> +			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER)) {
> +		dev_err(smmu->dev, "Unable to add link to the consumer %s\n",
> +			dev_name(dev));
> +		ret = -ENODEV;
> +		goto out_unlink;
> +	}
> +
>  	return 0;
>  
> +out_unlink:
> +	iommu_device_unlink(&smmu->iommu, dev);
> +	arm_smmu_master_free_smes(fwspec);
>  out_cfg_free:
>  	kfree(cfg);
>  out_free:
>