Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c44e2cdd authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
Browse files

rcu: Check for idle-loop entry while in RCU read-side critical section 



The inner idle loop is an extended quiescent state for all flavors
of RCU, but there have been recent bug involving use of RCU read-side
primitives from within the idle loop.  Therefore, this commit enlists
lockdep-RCU to detect attempts to enter the inner idle loop while in
an RCU read-side critical section, emitting a lockdep-RCU splat if so.

Signed-off-by: default avatarPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 30fbcc90

kernel/rcutree.c

+11 −0
Original line number Diff line number Diff line
@@ -366,6 +366,17 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) 
	atomic_inc(&rdtp->dynticks);

	smp_mb__after_atomic_inc();  /* Force ordering with next sojourn. */

	WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);



	/*

	 * The idle task is not permitted to enter the idle loop while

	 * in an RCU read-side critical section.

	 */

	rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),

			   "Illegal idle entry in RCU read-side critical section.");

	rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map),

			   "Illegal idle entry in RCU-bh read-side critical section.");

	rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),

			   "Illegal idle entry in RCU-sched read-side critical section.");

}



/**