Commit a56ca561 authored by Boqun Feng's avatar Boqun Feng
Browse files

rcutorture: Update ->extendables check for lazy preemption 



The rcutorture_one_extend_check() function's second last check assumes
that "preempt_count() & PREEMPT_MASK" is non-zero only if
RCUTORTURE_RDR_PREEMPT or RCUTORTURE_RDR_SCHED bit is set.

This works for preemptible RCU and for non-preemptible RCU running in
a non-preemptible kernel.  But it fails for non-preemptible RCU running
in a preemptible kernel because then rcu_read_lock() is just
preempt_disable(), which increases preempt count.

This commit therefore adjusts this check to take into account the case
fo non-preemptible RCU running in a preemptible kernel.

Reviewed-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 0be4b19e

kernel/rcu/rcutorture.c

+10 −2
Original line number Diff line number Diff line
@@ -1901,8 +1901,16 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, 
	WARN_ONCE(cur_ops->extendables &&

		  !(curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) &&

		  (preempt_count() & SOFTIRQ_MASK), ROEC_ARGS);

	WARN_ONCE(cur_ops->extendables &&

		  !(curstate & (RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED)) &&



	/*

	 * non-preemptible RCU in a preemptible kernel uses preempt_disable()

	 * as rcu_read_lock().

	 */

	mask = RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;

	if (!IS_ENABLED(CONFIG_PREEMPT_RCU))

		mask |= RCUTORTURE_RDR_RCU_1 | RCUTORTURE_RDR_RCU_2;



	WARN_ONCE(cur_ops->extendables && !(curstate & mask) &&

		  (preempt_count() & PREEMPT_MASK), ROEC_ARGS);



	/*