From: Paul E. McKenney Date: Mon, 29 Oct 2018 11:53:01 +0100 Subject: [PATCH] EXP rcu: Revert expedited GP parallelization cleverness Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz (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 Signed-off-by: Paul E. McKenney Signed-off-by: Sebastian Andrzej Siewior --- kernel/rcu/tree_exp.h | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -472,7 +472,6 @@ static void sync_rcu_exp_select_node_cpu 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(str 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; }