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From: "Paul E. McKenney" <paulmck@linux.ibm.com>
Date: Mon, 29 Oct 2018 11:53:01 +0100
Subject: [PATCH 023/351] EXP rcu: Revert expedited GP parallelization
cleverness
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=f0bd926ced576e698b47251d7867b02d829e4115
(Commit 258ba8e089db23f760139266c232f01bad73f85c from linux-rcu)
This commit reverts a series of commits starting with fcc635436501 ("rcu:
Make expedited GPs handle CPU 0 being offline") and its successors, thus
queueing each rcu_node structure's expedited grace-period initialization
work on the first CPU of that rcu_node structure.
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/rcu/tree_exp.h | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 72770a551c24..ac6d6fdf5783 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -472,7 +472,6 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
smp_call_func_t func)
{
- int cpu;
struct rcu_node *rnp;
trace_rcu_exp_grace_period(rsp->name, rcu_exp_gp_seq_endval(rsp), TPS("reset"));
@@ -494,13 +493,7 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
continue;
}
INIT_WORK(&rnp->rew.rew_work, sync_rcu_exp_select_node_cpus);
- preempt_disable();
- cpu = cpumask_next(rnp->grplo - 1, cpu_online_mask);
- /* If all offline, queue the work on an unbound CPU. */
- if (unlikely(cpu > rnp->grphi))
- cpu = WORK_CPU_UNBOUND;
- queue_work_on(cpu, rcu_par_gp_wq, &rnp->rew.rew_work);
- preempt_enable();
+ queue_work_on(rnp->grplo, rcu_par_gp_wq, &rnp->rew.rew_work);
rnp->exp_need_flush = true;
}
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