From 07325d4a90d2d84de45cc07b134fd0f023dbb971 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 21 May 2020 22:05:16 +0200 Subject: rcu: Provide rcu_irq_exit_check_preempt() Provide a debug check which can be invoked from exception return to kernel mode before an attempt is made to schedule. Warn if RCU is not ready for this. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: Paul E. McKenney Link: https://lore.kernel.org/r/20200521202117.089709607@linutronix.de --- kernel/rcu/tree.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b7f8c494d1d1..d8e9dbbefcfa 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -765,6 +765,24 @@ void rcu_irq_exit_preempt(void) "RCU in extended quiescent state!"); } +#ifdef CONFIG_PROVE_RCU +/** + * rcu_irq_exit_check_preempt - Validate that scheduling is possible + */ +void rcu_irq_exit_check_preempt(void) +{ + lockdep_assert_irqs_disabled(); + + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0, + "RCU dynticks_nesting counter underflow/zero!"); + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) != + DYNTICK_IRQ_NONIDLE, + "Bad RCU dynticks_nmi_nesting counter\n"); + RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), + "RCU in extended quiescent state!"); +} +#endif /* #ifdef CONFIG_PROVE_RCU */ + /* * Wrapper for rcu_irq_exit() where interrupts are enabled. * -- cgit v1.2.3-70-g09d2