Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756762AbaGHTee (ORCPT ); Tue, 8 Jul 2014 15:34:34 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54778 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756749AbaGHTeb (ORCPT ); Tue, 8 Jul 2014 15:34:31 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Johan Hovold" , "Zhang, Qi1" , "xiao jin" , "David Cohen" Date: Tue, 08 Jul 2014 20:01:50 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 030/125] USB: usb_wwan: fix race between write and resume In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: xiao jin commit d9e93c08d8d985e5ef89436ebc9f4aad7e31559f upstream. We find a race between write and resume. usb_wwan_resume run play_delayed() and spin_unlock, but intfdata->suspended still is not set to zero. At this time usb_wwan_write is called and anchor the urb to delay list. Then resume keep running but the delayed urb have no chance to be commit until next resume. If the time of next resume is far away, tty will be blocked in tty_wait_until_sent during time. The race also can lead to writes being reordered. This patch put play_Delayed and intfdata->suspended together in the spinlock, it's to avoid the write race during resume. Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the option driver") Signed-off-by: xiao jin Signed-off-by: Zhang, Qi1 Reviewed-by: David Cohen Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: there's no need to check for portdata == NULL] Signed-off-by: Ben Hutchings --- drivers/usb/serial/usb_wwan.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/drivers/usb/serial/usb_wwan.c +++ b/drivers/usb/serial/usb_wwan.c @@ -731,17 +731,15 @@ int usb_wwan_resume(struct usb_serial *s } } + spin_lock_irq(&intfdata->susp_lock); for (i = 0; i < serial->num_ports; i++) { /* walk all ports */ port = serial->port[i]; portdata = usb_get_serial_port_data(port); /* skip closed ports */ - spin_lock_irq(&intfdata->susp_lock); - if (!portdata->opened) { - spin_unlock_irq(&intfdata->susp_lock); + if (!portdata->opened) continue; - } for (j = 0; j < N_IN_URB; j++) { urb = portdata->in_urbs[j]; @@ -754,9 +752,7 @@ int usb_wwan_resume(struct usb_serial *s } } play_delayed(port); - spin_unlock_irq(&intfdata->susp_lock); } - spin_lock_irq(&intfdata->susp_lock); intfdata->suspended = 0; spin_unlock_irq(&intfdata->susp_lock); err_out: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/