Re: [PATCH v3 04/18] driver core: platform: Add driver dma ownership management

[Lu Baolu]

On 12/7/21 9:16 PM, Jason Gunthorpe wrote:
> On Tue, Dec 07, 2021 at 10:57:25AM +0800, Lu Baolu wrote:
> > On 12/6/21 11:06 PM, Jason Gunthorpe wrote:
> > > On Mon, Dec 06, 2021 at 06:36:27AM -0800, Christoph Hellwig wrote:
> > > > I really hate the amount of boilerplate code that having this in each
> > > > bus type causes.
> > > +1
> > >
> > > I liked the first version of this series better with the code near
> > > really_probe().
> > >
> > > Can we go back to that with some device_configure_dma() wrapper
> > > condtionally called by really_probe as we discussed?
> >
> > Are you talking about below change?
> >
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> > index 68ea1f949daa..368f9e530515 100644
> > +++ b/drivers/base/dd.c
> > @@ -577,7 +577,13 @@ static int really_probe(struct device *dev, struct
> > device_driver *drv)
> >   	if (dev->bus->dma_configure) {
> >   		ret = dev->bus->dma_configure(dev);
> >   		if (ret)
> > -			goto probe_failed;
> > +			goto pinctrl_bind_failed;
> > +
> > +		if (!drv->no_kernel_dma) {
> > +			ret = iommu_device_set_dma_owner(dev, DMA_OWNER_DMA_API, NULL);
> > +			if (ret)
> > +				goto pinctrl_bind_failed;
> > +                }
> >   	}
>
> Yes, the suggestion was to put everything that 'if' inside a function
> and then of course a matching undo function.

Followed your suggestion, I refactored the change like below:

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 68ea1f949daa..68ca5a579eb1 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -538,6 +538,32 @@ static int call_driver_probe(struct device *dev, 
struct device_driver *drv)
        return ret;
 }

+static int device_dma_configure(struct device *dev, struct 
device_driver *drv)
+{
+       int ret;
+
+       if (!dev->bus->dma_configure)
+               return 0;
+
+       ret = dev->bus->dma_configure(dev);
+       if (ret)
+               return ret;
+
+       if (!drv->suppress_auto_claim_dma_owner)
+               ret = iommu_device_set_dma_owner(dev, DMA_OWNER_DMA_API, 
NULL);
+
+       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, 
NULL);
+}
+
 static int really_probe(struct device *dev, struct device_driver *drv)
 {
        bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
@@ -574,11 +600,8 @@ 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;

        ret = driver_sysfs_add(dev);
        if (ret) {
@@ -660,6 +683,8 @@ static int really_probe(struct device *dev, struct 
device_driver *drv)
        if (dev->bus)
                blocking_notifier_call_chain(&dev->bus->p->bus_notifier,

BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
+
+       device_dma_cleanup(dev, drv);
 pinctrl_bind_failed:
        device_links_no_driver(dev);
        devres_release_all(dev);
@@ -1204,6 +1229,7 @@ static void __device_release_driver(struct device 
*dev, struct device *parent)
                else if (drv->remove)
                        drv->remove(dev);

+               device_dma_cleanup(dev, drv);
                device_links_driver_cleanup(dev);

                devres_release_all(dev);
diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h
index a498ebcf4993..374a3c2cc10d 100644
--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h
@@ -100,6 +100,7 @@ struct device_driver {
        const char              *mod_name;      /* used for built-in 
modules */

        bool suppress_bind_attrs;       /* disables bind/unbind via 
sysfs */
+       bool suppress_auto_claim_dma_owner;
        enum probe_type probe_type;

        const struct of_device_id       *of_match_table;

Further suggestions?

Best regards,
baolu