From d24209bb689e2c7f7418faec9b4a948e922d24da Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 21 Jan 2015 15:26:03 -0800 Subject: rcu: Improve diagnostics for blocked critical sections in irq If an RCU read-side critical section occurs within an interrupt handler or a softirq handler, it cannot have been preempted. Therefore, there is a check in rcu_read_unlock_special() checking for this error. However, when this check triggers, it lacks diagnostic information. This commit therefore moves rcu_read_unlock()'s lockdep annotation to follow the call to __rcu_read_unlock() and changes rcu_read_unlock_special()'s WARN_ON_ONCE() to an lockdep_rcu_suspicious() in order to locate where the offending RCU read-side critical section began. In addition, the value of the ->rcu_read_unlock_special field is printed. Signed-off-by: Paul E. McKenney --- include/linux/lockdep.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'include/linux/lockdep.h') diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 74ab23176e9b..066ba4157541 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -531,8 +531,13 @@ do { \ # define might_lock_read(lock) do { } while (0) #endif -#ifdef CONFIG_PROVE_RCU +#ifdef CONFIG_LOCKDEP void lockdep_rcu_suspicious(const char *file, const int line, const char *s); +#else +static inline void +lockdep_rcu_suspicious(const char *file, const int line, const char *s) +{ +} #endif #endif /* __LINUX_LOCKDEP_H */ -- cgit v1.2.1