rcu: Make rcu_report_unblock_qs_rnp() warn on violated preconditions (c74859d1) · Commits · 戴 / test

If rcu_report_unblock_qs_rnp() is invoked on something other than preemptible RCU or if there are still preempted tasks blocking the current grace period, something went badly wrong in the caller. This commit therefore adds WARN_ON_ONCE() to these conditions, but leaving the legitimate reason for early exit (rnp->qsmask != 0) unwarned. Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2308,8 +2308,10 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
		struct rcu_node *rnp_p;

		raw_lockdep_assert_held_rcu_node(rnp);
		if (rcu_state_p == &rcu_sched_state \|\| rsp != rcu_state_p \|\|
		rnp->qsmask != 0 \|\| rcu_preempt_blocked_readers_cgp(rnp)) {
		if (WARN_ON_ONCE(rcu_state_p == &rcu_sched_state) \|\|
		WARN_ON_ONCE(rsp != rcu_state_p) \|\|
		WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)) \|\|
		rnp->qsmask != 0) {
		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
		return; /* Still need more quiescent states! */
		}

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