From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965533Ab3GSFX5 (ORCPT ); Fri, 19 Jul 2013 01:23:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39458 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965463Ab3GSFWb (ORCPT ); Fri, 19 Jul 2013 01:22:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, UCHINO Satoshi , Michal Nazarewicz , Felipe Balbi Subject: [ 09/38] usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed Date: Thu, 18 Jul 2013 22:21:25 -0700 Message-Id: <20130719052048.517099335@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <20130719052047.858393825@linuxfoundation.org> References: <20130719052047.858393825@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: UCHINO Satoshi commit d68c277b501889b3a50c179d1c3d704db7947b83 upstream. Without this memory barrier, the file-storage thread may fail to escape from the following while loop, because it may observe new common->thread_wakeup_needed and old bh->state which are updated by the callback functions. /* Wait for the CBW to arrive */ while (bh->state != BUF_STATE_FULL) { rc = sleep_thread(common); if (rc) return rc; } Signed-off-by: UCHINO Satoshi Acked-by: Michal Nazarewicz Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/f_mass_storage.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -413,6 +413,7 @@ static int fsg_set_halt(struct fsg_dev * /* Caller must hold fsg->lock */ static void wakeup_thread(struct fsg_common *common) { + smp_wmb(); /* ensure the write of bh->state is complete */ /* Tell the main thread that something has happened */ common->thread_wakeup_needed = 1; if (common->thread_task) @@ -632,6 +633,7 @@ static int sleep_thread(struct fsg_commo } __set_current_state(TASK_RUNNING); common->thread_wakeup_needed = 0; + smp_rmb(); /* ensure the latest bh->state is visible */ return rc; }