From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758989AbaGOM3D (ORCPT ); Tue, 15 Jul 2014 08:29:03 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:61513 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758714AbaGOM27 (ORCPT ); Tue, 15 Jul 2014 08:28:59 -0400 From: "Rafael J. Wysocki" To: Takashi Iwai Cc: Len Brown , Pavel Machek , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PM / sleep: Fix request_firmware() error at resume Date: Tue, 15 Jul 2014 14:47:13 +0200 Message-ID: <3026958.0fOrQtDZlF@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.16.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1405407087-19493-1-git-send-email-tiwai@suse.de> References: <1405407087-19493-1-git-send-email-tiwai@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, July 15, 2014 08:51:27 AM Takashi Iwai wrote: > 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 Applied, thanks for fixing this up! > --- > 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); > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.