| Message ID | 1405407087-19493-1-git-send-email-tiwai@suse.de (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
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: <stable@vger.kernel.org> > Signed-off-by: Takashi Iwai <tiwai@suse.de> 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); >
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);
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: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> --- kernel/power/process.c | 1 + 1 file changed, 1 insertion(+)