Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754224AbaG3MYw (ORCPT ); Wed, 30 Jul 2014 08:24:52 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:36771 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752987AbaG3MPd (ORCPT ); Wed, 30 Jul 2014 08:15:33 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Takashi Iwai , "Rafael J. Wysocki" , Jiri Slaby Subject: [PATCH 3.12 70/94] PM / sleep: Fix request_firmware() error at resume Date: Wed, 30 Jul 2014 14:14:59 +0200 Message-Id: X-Mailer: git-send-email 2.0.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Takashi Iwai 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- kernel/power/process.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/power/process.c b/kernel/power/process.c index 06ec8869dbf1..14f9a8d4725d 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); -- 2.0.1 -- 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/