rcu: Prevent false positive softirq warning on RT

Soft interrupt disabled sections can legitimately be preempted or schedule
out when blocking on a lock on RT enabled kernels so the RCU preempt check
warning has to be disabled for RT kernels.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210309085727.626304079@linutronix.de

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bd04f722714f65dea4791076d3f63feb5e16e3c9..6d855ef091ba55e798457f4099594f8f7ea90289 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -334,7 +334,8 @@ static inline void rcu_preempt_sleep_check(void) { }
 #define rcu_sleep_check()                                              \
        do {                                                            \
                rcu_preempt_sleep_check();                              \
-               RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),        \
+               if (!IS_ENABLED(CONFIG_PREEMPT_RT))                     \
+                   RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),    \
                                 "Illegal context switch in RCU-bh read-side critical section"); \
                RCU_LOCKDEP_WARN(lock_is_held(&rcu_sched_lock_map),     \
                                 "Illegal context switch in RCU-sched read-side critical section"); \