| From 170fad9e22df0063eba0701adb966786d7a4ec5a Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <jhovold@gmail.com> |
| Date: Mon, 26 May 2014 19:23:15 +0200 |
| Subject: USB: usb_wwan: fix write and suspend race |
| |
| From: Johan Hovold <jhovold@gmail.com> |
| |
| 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> |
| |
| --- |
| drivers/usb/serial/usb_wwan.c | 13 +++++-------- |
| 1 file changed, 5 insertions(+), 8 deletions(-) |
| |
| --- 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 |
| 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; |