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

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Message-ID: <20180925151711.7ea1cf75@jacob-builder>
Date:   Tue, 25 Sep 2018 15:17:11 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Jean-Philippe Brucker <jean-philippe.brucker@....com>
Cc:     "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>,
        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>,
        jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API

On Tue, 25 Sep 2018 15:58:41 +0100
Jean-Philippe Brucker <jean-philippe.brucker@....com> wrote:

> 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?
> 
sounds good.

	if (!param || param->fault_param)
		return -EINVAL;

> > +       /* 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 ||
> 
your are right, thanks!