linux-kernel - Re: [PATCH v4 06/35] iommu/mediatek: Add mutex for m4u_group and m4u

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Message-ID: <62d2a231-3d05-5008-fae2-335c4ad853bd@collabora.com>
Date:   Thu, 27 Jan 2022 12:02:08 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Will Deacon <will@...nel.org>
Cc:     Robin Murphy <robin.murphy@....com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Tomasz Figa <tfiga@...omium.org>,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org,
        Hsin-Yi Wang <hsinyi@...omium.org>, youlin.pei@...iatek.com,
        anan.sun@...iatek.com, xueqi.zhang@...iatek.com,
        yen-chang.chen@...iatek.com, mingyuan.ma@...iatek.com,
        yf.wang@...iatek.com, libo.kang@...iatek.com,
        chengci.xu@...iatek.com
Subject: Re: [PATCH v4 06/35] iommu/mediatek: Add mutex for m4u_group and
 m4u_dom in data

Il 25/01/22 09:56, Yong Wu ha scritto:
> Add a mutex to protect the data in the structure mtk_iommu_data,
> like ->"m4u_group" ->"m4u_dom". For the internal data, we should
> protect it in ourselves driver. Add a mutex for this.
> This could be a fix for the multi-groups support.
> 
> Fixes: c3045f39244e ("iommu/mediatek: Support for multi domains")
> Signed-off-by: Yunfei Wang <yf.wang@...iatek.com>
> Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> ---
>   drivers/iommu/mtk_iommu.c | 13 +++++++++++--
>   drivers/iommu/mtk_iommu.h |  2 ++
>   2 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index ec2c387abf60..095736bfb7b4 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -464,15 +464,16 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
>   		dom->data = data;
>   	}
>   
> +	mutex_lock(&data->mutex);
>   	if (!data->m4u_dom) { /* Initialize the M4U HW */
>   		ret = pm_runtime_resume_and_get(m4udev);
>   		if (ret < 0)
> -			return ret;
> +			goto data_unlock;

In order to enhance human readability, I would rather propose:

			goto err_unlock;

Apart from this,
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

>   
>   		ret = mtk_iommu_hw_init(data);
>   		if (ret) {
>   			pm_runtime_put(m4udev);
> -			return ret;
> +			goto data_unlock;
>   		}
>   		data->m4u_dom = dom;
>   		writel(dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
> @@ -480,9 +481,14 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
>   
>   		pm_runtime_put(m4udev);
>   	}
> +	mutex_unlock(&data->mutex);
>   
>   	mtk_iommu_config(data, dev, true, domid);
>   	return 0;
> +
> +data_unlock:
> +	mutex_unlock(&data->mutex);
> +	return ret;
>   }
>   
>   static void mtk_iommu_detach_device(struct iommu_domain *domain,
> @@ -592,6 +598,7 @@ static struct iommu_group *mtk_iommu_device_group(struct device *dev)
>   	if (domid < 0)
>   		return ERR_PTR(domid);
>   
> +	mutex_lock(&data->mutex);
>   	group = data->m4u_group[domid];
>   	if (!group) {
>   		group = iommu_group_alloc();
> @@ -600,6 +607,7 @@ static struct iommu_group *mtk_iommu_device_group(struct device *dev)
>   	} else {
>   		iommu_group_ref_get(group);
>   	}
> +	mutex_unlock(&data->mutex);
>   	return group;
>   }
>   
> @@ -874,6 +882,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>   	}
>   
>   	platform_set_drvdata(pdev, data);
> +	mutex_init(&data->mutex);
>   
>   	ret = iommu_device_sysfs_add(&data->iommu, dev, NULL,
>   				     "mtk-iommu.%pa", &ioaddr);
> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> index f81fa8862ed0..f413546ac6e5 100644
> --- a/drivers/iommu/mtk_iommu.h
> +++ b/drivers/iommu/mtk_iommu.h
> @@ -80,6 +80,8 @@ struct mtk_iommu_data {
>   
>   	struct dma_iommu_mapping	*mapping; /* For mtk_iommu_v1.c */
>   
> +	struct mutex			mutex; /* Protect m4u_group/m4u_dom above */
> +
>   	struct list_head		list;
>   	struct mtk_smi_larb_iommu	larb_imu[MTK_LARB_NR_MAX];
>   };
>