This is a note to let you know that I've just added the patch titled
PM / sleep: Fix request_firmware() error at resume
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pm-sleep-fix-request_firmware-error-at-resume.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4320f6b1d9db4ca912c5eb6ecb328b2e090e1586 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Tue, 15 Jul 2014 08:51:27 +0200
Subject: PM / sleep: Fix request_firmware() error at resume
From: Takashi Iwai <tiwai@xxxxxxx>
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 <tiwai@xxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/power/process.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -185,6 +185,7 @@ void thaw_processes(void)
printk("Restarting tasks ... ");
+ __usermodehelper_set_disable_depth(UMH_FREEZING);
thaw_workqueues();
read_lock(&tasklist_lock);
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.4/pm-sleep-fix-request_firmware-error-at-resume.patch
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