From f3612304ee04a1a36ded7604771ea56d818158cb Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 17 Feb 2012 10:29:20 +0100 Subject: [PATCH] [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 --- arch/s390/kernel/process.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 3201ae44799..4261aa79977 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(); -- 2.41.0