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 08:13:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     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

On Thu, Dec 23, 2021 at 11:02:54AM +0800, Lu Baolu wrote:
> 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.

If this is a bug in the existing kernel, please submit it as a separate
patch so that it can be properly backported to all affected kernels.
Never bury it in an unrelated change that will never get sent to older
kernels.

greg k-h