linux-kernel - [PATCH 013/100] usb: gadget: fix a bug and a WARN

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Date:	Fri, 11 Oct 2013 11:40:43 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Felipe Balbi <balbi@...com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 013/100] usb: gadget: fix a bug and a WARN_ON in dummy-hcd

3.5.7.23 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alan Stern <stern@...land.harvard.edu>

commit 5f5610f69be3a925b1f79af27150bb7377bc9ad6 upstream.

This patch fixes a NULL pointer dereference and a WARN_ON in
dummy-hcd.  These things were the result of moving to the UDC core
framework, and possibly of changes to that framework.

Now unloading a gadget driver causes the UDC to be stopped after the
gadget driver is unbound, not before.  Therefore the "driver" argument
to dummy_udc_stop() can be NULL, so we must not try to print the
driver's name without checking first.

Also, the UDC framework automatically unregisters the gadget when the
UDC is deleted.  Therefore a sysfs attribute file attached to the
gadget must be removed before the UDC is deleted, not after.

Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@...com>
[ luis: backported to 3.5: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/usb/gadget/dummy_hcd.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index 4ad1f1c..1e0f8cd 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -921,8 +921,9 @@ static int dummy_udc_stop(struct usb_gadget *g,
 	struct dummy_hcd	*dum_hcd = gadget_to_dummy_hcd(g);
 	struct dummy		*dum = dum_hcd->dum;
 
-	dev_dbg(udc_dev(dum), "unregister gadget driver '%s'\n",
-			driver->driver.name);
+	if (driver)
+		dev_dbg(udc_dev(dum), "unregister gadget driver '%s'\n",
+				driver->driver.name);
 
 	dum->driver = NULL;
 
@@ -1011,9 +1012,9 @@ static int dummy_udc_remove(struct platform_device *pdev)
 {
 	struct dummy	*dum = platform_get_drvdata(pdev);
 
-	usb_del_gadget_udc(&dum->gadget);
 	platform_set_drvdata(pdev, NULL);
 	device_remove_file(&dum->gadget.dev, &dev_attr_function);
+	usb_del_gadget_udc(&dum->gadget);
 	device_unregister(&dum->gadget.dev);
 	return 0;
 }
-- 
1.8.3.2

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