From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756832AbaHHUmD (ORCPT ); Fri, 8 Aug 2014 16:42:03 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40162 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756498AbaHHUlt (ORCPT ); Fri, 8 Aug 2014 16:41:49 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Takashi Iwai , "Rafael J. Wysocki" , Kamal Mostafa Subject: [PATCH 3.13 135/259] PM / sleep: Fix request_firmware() error at resume Date: Fri, 8 Aug 2014 13:39:18 -0700 Message-Id: <1407530482-4483-136-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 4320f6b1d9db4ca912c5eb6ecb328b2e090e1586 upstream. The commit [247bc037: PM / Sleep: Mitigate race between the freezer and request_firmware()] introduced the finer state control, but it also leads to a new bug; for example, a bug report regarding the firmware loading of intel BT device at suspend/resume: https://bugzilla.novell.com/show_bug.cgi?id=873790 The root cause seems to be a small window between the process resume and the clear of usermodehelper lock. The request_firmware() function checks the UMH lock and gives up when it's in UMH_DISABLE state. This is for avoiding the invalid f/w loading during suspend/resume phase. The problem is, however, that usermodehelper_enable() is called at the end of thaw_processes(). Thus, a thawed process in between can kick off the f/w loader code path (in this case, via btusb_setup_intel()) even before the call of usermodehelper_enable(). Then usermodehelper_read_trylock() returns an error and request_firmware() spews WARN_ON() in the end. This oneliner patch fixes the issue just by setting to UMH_FREEZING state again before restarting tasks, so that the call of request_firmware() will be blocked until the end of this function instead of returning an error. Fixes: 247bc0374254 (PM / Sleep: Mitigate race between the freezer and request_firmware()) Link: https://bugzilla.novell.com/show_bug.cgi?id=873790 Signed-off-by: Takashi Iwai Signed-off-by: Rafael J. Wysocki Signed-off-by: Kamal Mostafa --- kernel/power/process.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/power/process.c b/kernel/power/process.c index 06ec886..14f9a8d 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -184,6 +184,7 @@ void thaw_processes(void) printk("Restarting tasks ... "); + __usermodehelper_set_disable_depth(UMH_FREEZING); thaw_workqueues(); read_lock(&tasklist_lock); -- 1.9.1