Re: [patch V2 6/9] rcu: Prevent false positive softirq warning on RT

[Paul E. McKenney]

On Fri, Dec 04, 2020 at 06:01:57PM +0100, Thomas Gleixner wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxx>

Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>

> ---
>  include/linux/rcupdate.h |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -319,7 +319,8 @@ static inline void rcu_preempt_sleep_che
>  #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"); \
>