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[PATCH 5/7] USB: of: fix root-hub device-tree node handling

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  [PATCH 5/7] USB: of: fix root-hub device-tree node handling Johan Hovold <johan@kernel.org> - 2017-05-30 18:30 +0200
    Re: [PATCH 5/7] USB: of: fix root-hub device-tree node handling Johan Hovold <johan@kernel.org> - 2017-06-06 17:50 +0200

#1653354 — [PATCH 5/7] USB: of: fix root-hub device-tree node handling

In an attempt to work around a pinmux over-allocation issue in driver
core, commit dc5878abf49c ("usb: core: move root hub's device node
assignment after it is added to bus") moved the device-tree node
assignment until after the root hub had been registered.

This not only makes the device-tree node unavailable to the usb driver
during probe, but also prevents the of_node from being linked to in
sysfs and causes a race with user-space for the (recently added) devspec
attribute.

Use the new device_set_of_node_from_dev() helper to reuse the node of
the sysdev device, something which now prevents driver core from trying
to reclaim any pinctrl pins during probe.

Fixes: dc5878abf49c ("usb: core: move root hub's device node assignment after it is added to bus")
Fixes: 51fa91475e43 ("usb/core: Added devspec sysfs entry for devices behind the usb hub")
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/core/hcd.c | 2 --
 drivers/usb/core/usb.c | 4 ++--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 5dea98358c05..2cff59e9c268 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1076,7 +1076,6 @@ static void usb_deregister_bus (struct usb_bus *bus)
 static int register_root_hub(struct usb_hcd *hcd)
 {
 	struct device *parent_dev = hcd->self.controller;
-	struct device *sysdev = hcd->self.sysdev;
 	struct usb_device *usb_dev = hcd->self.root_hub;
 	const int devnum = 1;
 	int retval;
@@ -1123,7 +1122,6 @@ static int register_root_hub(struct usb_hcd *hcd)
 		/* Did the HC die before the root hub was registered? */
 		if (HCD_DEAD(hcd))
 			usb_hc_died (hcd);	/* This time clean up */
-		usb_dev->dev.of_node = sysdev->of_node;
 	}
 	mutex_unlock(&usb_bus_idr_lock);
 
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 62e1906bb2f3..17681d5638ac 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -416,8 +416,7 @@ static void usb_release_dev(struct device *dev)
 
 	usb_destroy_configuration(udev);
 	usb_release_bos_descriptor(udev);
-	if (udev->parent)
-		of_node_put(dev->of_node);
+	of_node_put(dev->of_node);
 	usb_put_hcd(hcd);
 	kfree(udev->product);
 	kfree(udev->manufacturer);
@@ -616,6 +615,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 		dev->route = 0;
 
 		dev->dev.parent = bus->controller;
+		device_set_of_node_from_dev(&dev->dev, bus->sysdev);
 		dev_set_name(&dev->dev, "usb%d", bus->busnum);
 		root_hub = 1;
 	} else {
-- 
2.13.0

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#1658878

On Mon, Jun 05, 2017 at 12:51:04PM +0800, Peter Chen wrote:
> On Tue, May 30, 2017 at 06:25:52PM +0200, Johan Hovold wrote:
> > In an attempt to work around a pinmux over-allocation issue in driver
> > core, commit dc5878abf49c ("usb: core: move root hub's device node
> > assignment after it is added to bus") moved the device-tree node
> > assignment until after the root hub had been registered.
> > 
> > This not only makes the device-tree node unavailable to the usb driver
> > during probe, but also prevents the of_node from being linked to in
> > sysfs and causes a race with user-space for the (recently added) devspec
> > attribute.
> > 
> > Use the new device_set_of_node_from_dev() helper to reuse the node of
> > the sysdev device, something which now prevents driver core from trying
> > to reclaim any pinctrl pins during probe.
> > 
> > Fixes: dc5878abf49c ("usb: core: move root hub's device node assignment after it is added to bus")
> > Fixes: 51fa91475e43 ("usb/core: Added devspec sysfs entry for devices behind the usb hub")
> > Signed-off-by: Johan Hovold <johan@kernel.org>

> I am OK with it, but I suggest adding it for new rc1 since it is based
> on the 1st patch which is a bug-fix. If this one is really needed for
> stable tree in future, you can cherry-pick it.

I agree, and didn't intent for this one to go into 4.12-rc. Let's see
how Greg wants to handle this. I'll add some comments to the cover
letter in v2.

Thanks,
Johan

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