From: Heiko Carstens Date: Fri, 17 Feb 2012 09:29:20 +0000 (+0100) Subject: [S390] idle: avoid RCU usage in extended quiescent state X-Git-Tag: firefly_0821_release~3680^2~3507^2~3 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f3612304ee04a1a36ded7604771ea56d818158cb;p=firefly-linux-kernel-4.4.55.git [S390] idle: avoid RCU usage in extended quiescent state Avoid calling wake_up() from our NMI "bottom halve" from RCU extended quiescent state in idle. wake_up() has RCU read-side critical sections but this will be completely ignored by RCU if the cpu is in extended quiescent state. Which means that whatever object is being accessed from within the read-side critical section can be freed concurrently from a different cpu. So make sure we leave extended quiescent state before calling wake_up(). Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 3201ae447990..4261aa799774 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -76,7 +76,6 @@ static void default_idle(void) if (test_thread_flag(TIF_MCCK_PENDING)) { local_mcck_enable(); local_irq_enable(); - s390_handle_mcck(); return; } trace_hardirqs_on(); @@ -93,10 +92,12 @@ void cpu_idle(void) for (;;) { tick_nohz_idle_enter(); rcu_idle_enter(); - while (!need_resched()) + while (!need_resched() && !test_thread_flag(TIF_MCCK_PENDING)) default_idle(); rcu_idle_exit(); tick_nohz_idle_exit(); + if (test_thread_flag(TIF_MCCK_PENDING)) + s390_handle_mcck(); preempt_enable_no_resched(); schedule(); preempt_disable();