From: Takashi Iwai Date: Tue, 15 Jul 2014 06:51:27 +0000 (+0200) Subject: PM / sleep: Fix request_firmware() error at resume X-Git-Tag: v3.16-rc6~19^2^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4320f6b1d9db4ca912c5eb6ecb328b2e090e1586;p=platform%2Fkernel%2Flinux-stable.git 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+ # 3.4+ Signed-off-by: Takashi Iwai Signed-off-by: Rafael J. Wysocki --- diff --git a/kernel/power/process.c b/kernel/power/process.c index 0ca8d83..4ee194e 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);