linux-kernel - Re: [PATCH v4 02/13] driver core: Set DMA ownership during driver bind/unbind

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Date:   Thu, 23 Dec 2021 11:02:54 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
        Diana Craciun <diana.craciun@....nxp.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Li Yang <leoyang.li@....com>,
        Dmitry Osipenko <digetx@...il.com>,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 02/13] driver core: Set DMA ownership during driver
 bind/unbind

Hi Greg,

On 12/22/21 8:47 PM, Greg Kroah-Hartman wrote:
>> +
>> +	return ret;
>> +}
>> +
>> +static void device_dma_cleanup(struct device *dev, struct device_driver *drv)
>> +{
>> +	if (!dev->bus->dma_configure)
>> +		return;
>> +
>> +	if (!drv->suppress_auto_claim_dma_owner)
>> +		iommu_device_release_dma_owner(dev, DMA_OWNER_DMA_API);
>> +}
>> +
>>   static int really_probe(struct device *dev, struct device_driver *drv)
>>   {
>>   	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
>> @@ -574,11 +601,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>>   	if (ret)
>>   		goto pinctrl_bind_failed;
>>   
>> -	if (dev->bus->dma_configure) {
>> -		ret = dev->bus->dma_configure(dev);
>> -		if (ret)
>> -			goto probe_failed;
>> -	}
>> +	if (device_dma_configure(dev, drv))
>> +		goto pinctrl_bind_failed;
> Are you sure you are jumping to the proper error path here?  It is not
> obvious why you changed this.

The error handling path in really_probe() seems a bit wrong. For
example,

  572         /* If using pinctrl, bind pins now before probing */
  573         ret = pinctrl_bind_pins(dev);
  574         if (ret)
  575                 goto pinctrl_bind_failed;

[...]

  663 pinctrl_bind_failed:
  664         device_links_no_driver(dev);
  665         devres_release_all(dev);
  666         arch_teardown_dma_ops(dev);
  667         kfree(dev->dma_range_map);
  668         dev->dma_range_map = NULL;
  669         driver_sysfs_remove(dev);
              ^^^^^^^^^^^^^^^^^^^^^^^^^
  670         dev->driver = NULL;
  671         dev_set_drvdata(dev, NULL);
  672         if (dev->pm_domain && dev->pm_domain->dismiss)
  673                 dev->pm_domain->dismiss(dev);
  674         pm_runtime_reinit(dev);
  675         dev_pm_set_driver_flags(dev, 0);
  676 done:
  677         return ret;

The driver_sysfs_remove() will be called even driver_sysfs_add() hasn't
been called yet. I can fix this in a separated patch if I didn't miss
anything.

Best regards,
baolu