USB: usb_wwan: fix write and suspend race
commit 170fad9e22df0063eba0701adb966786d7a4ec5a upstream.
Fix race between write() and suspend() which could lead to writes being
dropped (or I/O while suspended) if the device is runtime suspended
while a write request is being processed.
Specifically, suspend() releases the susp_lock after determining the
device is idle but before setting the suspended flag, thus leaving a
window where a concurrent write() can submit an urb.
Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the
option driver")
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 3dc899b..f2422ec 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -583,20 +583,17 @@
int usb_wwan_suspend(struct usb_serial *serial, pm_message_t message)
{
struct usb_wwan_intf_private *intfdata = serial->private;
- int b;
-
- if (PMSG_IS_AUTO(message)) {
- spin_lock_irq(&intfdata->susp_lock);
- b = intfdata->in_flight;
- spin_unlock_irq(&intfdata->susp_lock);
-
- if (b)
- return -EBUSY;
- }
spin_lock_irq(&intfdata->susp_lock);
+ if (PMSG_IS_AUTO(message)) {
+ if (intfdata->in_flight) {
+ spin_unlock_irq(&intfdata->susp_lock);
+ return -EBUSY;
+ }
+ }
intfdata->suspended = 1;
spin_unlock_irq(&intfdata->susp_lock);
+
stop_read_write_urbs(serial);
return 0;