USB: serial: fix runtime PM after driver unbind

BugLink: https://bugs.launchpad.net/bugs/1850541
commit d51bdb93ca7e71d7fb30a572c7b47ed0194bf3fe 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")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191001084908.2003-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 790e0cbe3da9ee3f6ca3f5d25d08cb1a1c38f297..1d7d5f50854be5a3c253b3afaaa5d5c6ee106c1d 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -311,10 +311,7 @@ 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);