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")
Cc: <[email protected]> # v2.6.32
Signed-off-by: Johan Hovold <[email protected]>
---
drivers/usb/serial/usb_wwan.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 112693a4100b..2b8f02696c00 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -579,20 +579,17 @@ static void stop_read_write_urbs(struct usb_serial
*serial)
int usb_wwan_suspend(struct usb_serial *serial, pm_message_t message)
{
struct usb_wwan_intf_private *intfdata = serial->private;
- int b;
+ spin_lock_irq(&intfdata->susp_lock);
if (PMSG_IS_AUTO(message)) {
- spin_lock_irq(&intfdata->susp_lock);
- b = intfdata->in_flight;
- spin_unlock_irq(&intfdata->susp_lock);
-
- if (b)
+ if (intfdata->in_flight) {
+ spin_unlock_irq(&intfdata->susp_lock);
return -EBUSY;
+ }
}
-
- spin_lock_irq(&intfdata->susp_lock);
intfdata->suspended = 1;
spin_unlock_irq(&intfdata->susp_lock);
+
stop_read_write_urbs(serial);
return 0;
--
1.8.5.5
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