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Commit a8f4cbad authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Shorten irq-disable region in rcu_cleanup_dead_cpu() 



Now that we are not migrating callbacks, there is no need to hold the
->orphan_lock across the the ->qsmaskinit bit-clearing process.
This commit therefore releases ->orphan_lock immediately after adopting
the orphaned RCU callbacks.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent d19fb8d1

kernel/rcu/tree.c

+2 −2
Original line number Diff line number Diff line
@@ -2289,14 +2289,14 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) 
	/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */

	rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);

	rcu_adopt_orphan_cbs(rsp, flags);

	raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);



	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */

	raw_spin_lock(&rnp->lock);	/* irqs already disabled. */

	raw_spin_lock_irqsave(&rnp->lock, flags);

	smp_mb__after_unlock_lock();	/* Enforce GP memory-order guarantee. */

	rnp->qsmaskinit &= ~rdp->grpmask;

	if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp))

		rcu_cleanup_dead_rnp(rnp);

	raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */

	raw_spin_unlock_irqrestore(&rnp->lock, flags);

	WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,

		  "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",