linux-kernel - [PATCH 3/4] USB: serial: fix runtime PM after driver unbind

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Message-Id: <20190930161205.18803-4-johan@kernel.org>
Date:   Mon, 30 Sep 2019 18:12:04 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Pete Zaitcev <zaitcev@...hat.com>,
        Alan Stern <stern@...land.harvard.edu>,
        linux-media@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        stable <stable@...r.kernel.org>
Subject: [PATCH 3/4] USB: serial: fix runtime PM after driver unbind

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")
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/usb/serial/usb-serial.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index a3179fea38c8..8f066bb55d7d 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -314,10 +314,7 @@ static void serial_cleanup(struct tty_struct *tty)
 	serial = port->serial;
 	owner = serial->type->driver.owner;
 
-	mutex_lock(&serial->disc_mutex);
-	if (!serial->disconnected)
-		usb_autopm_put_interface(serial->interface);
-	mutex_unlock(&serial->disc_mutex);
+	usb_autopm_put_interface(serial->interface);
 
 	usb_serial_put(serial);
 	module_put(owner);
-- 
2.23.0