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author | Takashi Iwai <tiwai@suse.de> | 2014-07-15 08:51:27 +0200 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-07-15 14:27:29 +0200 |
commit | 4320f6b1d9db4ca912c5eb6ecb328b2e090e1586 (patch) | |
tree | fa0aff03571ae1543c2f8be9c87abcddc074f753 /kernel | |
parent | 1795cd9b3a91d4b5473c97f491d63892442212ab (diff) | |
download | linux-4320f6b1d9db4ca912c5eb6ecb328b2e090e1586.tar.bz2 |
PM / sleep: Fix request_firmware() error at resume
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
Cc: 3.4+ <stable@vger.kernel.org> # 3.4+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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 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); |