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rcu: Note quiescent state when CPU goes offline

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The rcu_cleanup_dead_cpu() function (called after a CPU has gone
completely offline) has not reported a quiescent state because there
was probably at least one synchronize_rcu() between the time the CPU
went offline and the CPU_DEAD notifier, and this would have detected
the CPU's offline state via quiescent-state forcing.  However, the plan
is for CPUs to take themselves offline, at which point it makes sense
for them to report their own quiescent state.  This commit makes this
change in preparation for the new CPU-hotplug setup.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2014-11-12 09:57:51 -08:00
parent 5d0b024973
commit 3ba4d0e09b
1 changed files with 1 additions and 1 deletions
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kernel/rcu/tree.c
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@ -2297,7 +2297,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
rnp->qsmaskinit &= ~rdp->grpmask;
if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp))
rcu_cleanup_dead_rnp(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
rcu_report_qs_rnp(rdp->grpmask, rsp, rnp, flags); /* Rlses rnp->lock. */
WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
cpu, rdp->qlen, rdp->nxtlist);