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USB: usb_wwan: fix write and suspend race

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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: 383cedc3bb ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2014-05-26 19:23:15 +02:00 committed by Greg Kroah-Hartman
parent d9e93c08d8
commit 170fad9e22
1 changed files with 7 additions and 10 deletions
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17
drivers/usb/serial/usb_wwan.c
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@ -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;
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;