[PATCH 3.16.y-ckt 127/133] usbnet: Get EVENT_NO_RUNTIME_PM bit before it is cleared

From: Luis Henriques
Date: Wed Sep 30 2015 - 05:57:28 EST

3.16.7-ckt18 -stable review patch. If anyone has any objections, please let me know.


From: Eugene Shatokhin <eugene.shatokhin@xxxxxxxxxx>

commit f50791ac1aca1ac1b0370d62397b43e9f831421a upstream.

It is needed to check EVENT_NO_RUNTIME_PM bit of dev->flags in
usbnet_stop(), but its value should be read before it is cleared
when dev->flags is set to 0.

The problem was spotted and the fix was provided by
Oliver Neukum <oneukum@xxxxxxx>.

Signed-off-by: Eugene Shatokhin <eugene.shatokhin@xxxxxxxxxx>
Acked-by: Oliver Neukum <oneukum@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
drivers/net/usb/usbnet.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index c5a2ad29d53c..5d819dde448d 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -778,7 +778,7 @@ int usbnet_stop (struct net_device *net)
struct usbnet *dev = netdev_priv(net);
struct driver_info *info = dev->driver_info;
- int retval, pm;
+ int retval, pm, mpn;

clear_bit(EVENT_DEV_OPEN, &dev->flags);
netif_stop_queue (net);
@@ -809,6 +809,8 @@ int usbnet_stop (struct net_device *net)


+ mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
/* deferred work (task, timer, softirq) must also stop.
* can't flush_scheduled_work() until we drop rtnl (later),
* else workers could deadlock; so make workers a NOP.
@@ -819,8 +821,7 @@ int usbnet_stop (struct net_device *net)
if (!pm)

- if (info->manage_power &&
- !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
+ if (info->manage_power && mpn)
info->manage_power(dev, 0);
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