linux-kernel - Re: [PATCH v5 13/23] iommu: introduce device fault report API

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Message-ID: <130edd60-d92a-9871-334b-943fe8acffee@arm.com>
Date:   Tue, 25 Sep 2018 15:58:41 +0100
From:   Jean-Philippe Brucker <jean-philippe.brucker@....com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     Rafael Wysocki <rafael.j.wysocki@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Jean Delvare <khali@...ux-fr.org>,
        Christoph Hellwig <hch@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API

Hi Jacob,

Just two minor things below, that I noticed while using fault handlers
for SVA. From my perspective the series is fine otherwise

On 11/05/2018 21:54, Jacob Pan wrote:
> +int iommu_unregister_device_fault_handler(struct device *dev)
> +{
> +       struct iommu_param *param = dev->iommu_param;
> +       int ret = 0;
> +
> +       if (!param)
> +               return -EINVAL;
> +
> +       mutex_lock(&param->lock);

Could we check that param->fault_param isn't NULL here, so that the
driver can call this function unconditionally in a cleanup path?

> +       /* we cannot unregister handler if there are pending faults */
> +       if (!list_empty(&param->fault_param->faults)) {
> +               ret = -EBUSY;
> +               goto unlock;
> +       }
> +
> +       kfree(param->fault_param);
> +       param->fault_param = NULL;
> +       put_device(dev);
> +unlock:
> +       mutex_unlock(&param->lock);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler);
> +
> +
> +/**
> + * iommu_report_device_fault() - Report fault event to device
> + * @dev: the device
> + * @evt: fault event data
> + *
> + * Called by IOMMU model specific drivers when fault is detected, typically
> + * in a threaded IRQ handler.
> + *
> + * Return 0 on success, or an error.
> + */
> +int iommu_report_device_fault(struct device *dev, struct
> iommu_fault_event *evt)
> +{
> +       int ret = 0;
> +       struct iommu_fault_event *evt_pending;
> +       struct iommu_fault_param *fparam;
> +
> +       /* iommu_param is allocated when device is added to group */
> +       if (!dev->iommu_param | !evt)

Should probably be ||

Thanks,
Jean