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[3.11,166/198] USB: cdc-acm: fix runtime PM imbalance at shutdown

Message ID 1404379241-8590-167-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques July 3, 2014, 9:20 a.m. UTC 
3.11.10.13 -stable review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <jhovold@gmail.com>

commit 5292afa657d0e790b7479ad8eef9450c1e040b3d upstream.

Make sure only to decrement the PM counters if they were actually
incremented.

Note that the USB PM counter, but not necessarily the driver core PM
counter, is reset when the interface is unbound.

Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/usb/class/cdc-acm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 83a19ae3c31c..a72b7f1f6e17 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -575,12 +575,13 @@  static void acm_port_shutdown(struct tty_port *port)
 	struct urb *urb;
 	struct acm_wb *wb;
 	int i;
+	int pm_err;
 
 	dev_dbg(&acm->control->dev, "%s\n", __func__);
 
 	mutex_lock(&acm->mutex);
 	if (!acm->disconnected) {
-		usb_autopm_get_interface(acm->control);
+		pm_err = usb_autopm_get_interface(acm->control);
 		acm_set_control(acm, acm->ctrlout = 0);
 
 		for (;;) {
@@ -598,7 +599,8 @@  static void acm_port_shutdown(struct tty_port *port)
 		for (i = 0; i < acm->rx_buflimit; i++)
 			usb_kill_urb(acm->read_urbs[i]);
 		acm->control->needs_remote_wakeup = 0;
-		usb_autopm_put_interface(acm->control);
+		if (!pm_err)
+			usb_autopm_put_interface(acm->control);
 	}
 	mutex_unlock(&acm->mutex);
 }