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| author | Takashi Iwai <tiwai@suse.de> | 2014-07-15 08:51:27 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-28 08:06:03 -0700 |
| commit | 9abefe6933601246129da98d6c16936547a5cc8e (patch) | |
| tree | 3bdf61d9eee4319187160849009923134f5e8fe8 /kernel | |
| parent | 5b7d98d5e2f7496ca2254b6d628f1158ada1e7c2 (diff) | |
| download | kernel-common-9abefe6933601246129da98d6c16936547a5cc8e.tar.gz kernel-common-9abefe6933601246129da98d6c16936547a5cc8e.tar.bz2 kernel-common-9abefe6933601246129da98d6c16936547a5cc8e.zip | |
PM / sleep: Fix request_firmware() error at resume
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@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/power/process.c | 1 |
1 files changed, 1 insertions, 0 deletions
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); |