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

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Date:   Wed, 26 Sep 2018 11:14:05 +0100
From:   Jean-Philippe Brucker <jean-philippe.brucker@....com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.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>
Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API

On 25/09/2018 23:17, Jacob Pan wrote:
> 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;

That would be too convenient... param needs to be checked before taking
the lock, and fault_param accessed after

Thanks,
Jean