linux-kernel - [PATCH 3.16 033/136] USB: usb-skeleton: fix runtime PM after driver unbind

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Message-ID: <lsq.1576543535.819253251@decadent.org.uk>
Date:   Tue, 17 Dec 2019 00:46:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Johan Hovold" <johan@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.16 033/136] USB: usb-skeleton: fix runtime PM after
 driver unbind

3.16.80-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <johan@...nel.org>

commit 5c290a5e42c3387e82de86965784d30e6c5270fd upstream.

Since commit c2b71462d294 ("USB: core: Fix bug caused by duplicate
interface PM usage counter") USB drivers must always balance their
runtime PM gets and puts, including when the driver has already been
unbound from the interface.

Leaving the interface with a positive PM usage counter would prevent a
later bound driver from suspending the device.

Fixes: c2b71462d294 ("USB: core: Fix bug caused by duplicate interface PM usage counter")
Signed-off-by: Johan Hovold <johan@...nel.org>
Link: https://lore.kernel.org/r/20191001084908.2003-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/usb-skeleton.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -75,6 +75,7 @@ static void skel_delete(struct kref *kre
 	struct usb_skel *dev = to_skel_dev(kref);
 
 	usb_free_urb(dev->bulk_in_urb);
+	usb_put_intf(dev->interface);
 	usb_put_dev(dev->udev);
 	kfree(dev->bulk_in_buffer);
 	kfree(dev);
@@ -126,10 +127,7 @@ static int skel_release(struct inode *in
 		return -ENODEV;
 
 	/* allow the device to be autosuspended */
-	mutex_lock(&dev->io_mutex);
-	if (dev->interface)
-		usb_autopm_put_interface(dev->interface);
-	mutex_unlock(&dev->io_mutex);
+	usb_autopm_put_interface(dev->interface);
 
 	/* decrement the count on our device */
 	kref_put(&dev->kref, skel_delete);
@@ -511,7 +509,7 @@ static int skel_probe(struct usb_interfa
 	init_waitqueue_head(&dev->bulk_in_wait);
 
 	dev->udev = usb_get_dev(interface_to_usbdev(interface));
-	dev->interface = interface;
+	dev->interface = usb_get_intf(interface);
 
 	/* set up the endpoint information */
 	/* use only the first bulk-in and bulk-out endpoints */