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rcu: Shorten irq-disable region in rcu_cleanup_dead_cpu()

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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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2014-10-31 13:48:41 -07:00
parent d19fb8d1f3
commit a8f4cbadfb
1 changed files with 2 additions and 2 deletions
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4
kernel/rcu/tree.c
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@ -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",