From patchwork Wed Jul 17 22:45:49 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 259810 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id F21042C008C for ; Thu, 18 Jul 2013 08:51:10 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzaYq-0006of-FT; Wed, 17 Jul 2013 22:51:04 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzaWb-0006Ge-Op for kernel-team@lists.ubuntu.com; Wed, 17 Jul 2013 22:48:45 +0000 Received: from c-67-160-231-162.hsd1.ca.comcast.net ([67.160.231.162] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UzaWZ-0008C2-9d; Wed, 17 Jul 2013 22:48:43 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1UzaWX-0002Je-21; Wed, 17 Jul 2013 15:48:41 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 017/145] usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed Date: Wed, 17 Jul 2013 15:45:49 -0700 Message-Id: <1374101277-7915-18-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1374101277-7915-1-git-send-email-kamal@canonical.com> References: <1374101277-7915-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Cc: UCHINO Satoshi , Felipe Balbi X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.8.13.5 -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: Luis Henriques --- drivers/usb/gadget/f_mass_storage.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index 5d027b3..452e4f6 100644 --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -427,6 +427,7 @@ static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep) /* 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) @@ -646,6 +647,7 @@ static int sleep_thread(struct fsg_common *common) } __set_current_state(TASK_RUNNING); common->thread_wakeup_needed = 0; + smp_rmb(); /* ensure the latest bh->state is visible */ return rc; }