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Commit 2dee9404 authored by Paul E. McKenney's avatar Paul E. McKenney
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rcu: Add assertions verifying blocked-tasks list 



This commit adds assertions verifying the consistency of the rcu_node
structure's ->blkd_tasks list and its ->gp_tasks, ->exp_tasks, and
->boost_tasks pointers.  In particular, the ->blkd_tasks lists must be
empty except for leaf rcu_node structures.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 35fe723b

kernel/rcu/tree.c

+2 −0
Original line number Diff line number Diff line
@@ -2410,6 +2410,8 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp, 
			return;

		}

		WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */

		WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1 &&

			     rcu_preempt_blocked_readers_cgp(rnp));

		rnp->qsmask &= ~mask;

		trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,

						 mask, rnp->qsmask, rnp->level,

kernel/rcu/tree_plugin.h

+9 −2
Original line number Diff line number Diff line
@@ -180,6 +180,8 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) 
	struct task_struct *t = current;



	lockdep_assert_held(&rnp->lock);

	WARN_ON_ONCE(rdp->mynode != rnp);

	WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);



	/*

	 * Decide where to queue the newly blocked task.  In theory,
@@ -261,6 +263,10 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) 
		rnp->gp_tasks = &t->rcu_node_entry;

	if (!rnp->exp_tasks && (blkd_state & RCU_EXP_BLKD))

		rnp->exp_tasks = &t->rcu_node_entry;

	WARN_ON_ONCE(!(blkd_state & RCU_GP_BLKD) !=

		     !(rnp->qsmask & rdp->grpmask));

	WARN_ON_ONCE(!(blkd_state & RCU_EXP_BLKD) !=

		     !(rnp->expmask & rdp->grpmask));

	raw_spin_unlock_rcu_node(rnp); /* interrupts remain disabled. */



	/*
@@ -482,6 +488,7 @@ void rcu_read_unlock_special(struct task_struct *t) 
		rnp = t->rcu_blocked_node;

		raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */

		WARN_ON_ONCE(rnp != t->rcu_blocked_node);

		WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);

		empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);

		empty_exp = sync_rcu_preempt_exp_done(rnp);

		smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
@@ -495,10 +502,10 @@ void rcu_read_unlock_special(struct task_struct *t) 
		if (&t->rcu_node_entry == rnp->exp_tasks)

			rnp->exp_tasks = np;

		if (IS_ENABLED(CONFIG_RCU_BOOST)) {

			if (&t->rcu_node_entry == rnp->boost_tasks)

				rnp->boost_tasks = np;

			/* Snapshot ->boost_mtx ownership w/rnp->lock held. */

			drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;

			if (&t->rcu_node_entry == rnp->boost_tasks)

				rnp->boost_tasks = np;

		}



		/*