kernel/printk: Block cpuhotplug callback when tasks are frozen

The recent conversion of the console hotplug notifier to the state machine
missed the fact, that the notifier only operated on the non frozen
transitions. As a consequence the console_lock/unlock() pair is also
invoked during suspend, which results in a lockdep warning.

Restore the previous state by making the lock/unlock conditional on
!tasks_frozen.

Fixes: 90b14889d2f9 ("kernel/printk: Convert to hotplug state machine")
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1611171729320.3645@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 4487ffcd42d57ae6b47e10a08e140e54f18f1079..37893da9bae897a74dcac0317253f5a7de48b50f 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2194,8 +2194,10 @@ void resume_console(void)
  */
 static int console_cpu_notify(unsigned int cpu)
 {
-       console_lock();
-       console_unlock();
+       if (!cpuhp_tasks_frozen) {
+               console_lock();
+               console_unlock();
+       }
        return 0;
 }