From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757986AbaGOGvb (ORCPT ); Tue, 15 Jul 2014 02:51:31 -0400 Received: from cantor2.suse.de ([195.135.220.15]:45975 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757719AbaGOGv3 (ORCPT ); Tue, 15 Jul 2014 02:51:29 -0400 From: Takashi Iwai To: "Rafael J. Wysocki" Cc: Len Brown , Pavel Machek , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] PM / sleep: Fix request_firmware() error at resume Date: Tue, 15 Jul 2014 08:51:27 +0200 Message-Id: <1405407087-19493-1-git-send-email-tiwai@suse.de> X-Mailer: git-send-email 2.0.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=873790 Cc: Signed-off-by: Takashi Iwai --- kernel/power/process.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/power/process.c b/kernel/power/process.c index 0ca8d83e2369..4ee194eb524b 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -186,6 +186,7 @@ void thaw_processes(void) printk("Restarting tasks ... "); + __usermodehelper_set_disable_depth(UMH_FREEZING); thaw_workqueues(); read_lock(&tasklist_lock); -- 2.0.1