Commit-ID: b2454caa8977ade27292a71f2def5e403e24b4d5 Gitweb: http://git.kernel.org/tip/b2454caa8977ade27292a71f2def5e403e24b4d5 Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Thu, 10 Mar 2016 12:54:14 +0100 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Fri, 6 May 2016 14:58:24 +0200
sched/hotplug: Move sync_rcu to be with set_cpu_active(false) The sync_rcu stuff is specificically for clearing bits in the active mask, such that everybody will observe the bit cleared and will not consider the cleared CPU for load-balancing etc. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: r...@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.169219...@linutronix.de Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- kernel/cpu.c | 15 --------------- kernel/sched/core.c | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 15 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 15402b7..c134a35 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -703,21 +703,6 @@ static int takedown_cpu(unsigned int cpu) struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int err; - /* - * By now we've cleared cpu_active_mask, wait for all preempt-disabled - * and RCU users of this state to go away such that all new such users - * will observe it. - * - * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might - * not imply sync_sched(), so wait for both. - * - * Do sync before park smpboot threads to take care the rcu boost case. - */ - if (IS_ENABLED(CONFIG_PREEMPT)) - synchronize_rcu_mult(call_rcu, call_rcu_sched); - else - synchronize_rcu(); - /* Park the smpboot threads */ kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); smpboot_park_threads(cpu); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 73bcd93..0a31078 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7112,6 +7112,20 @@ int sched_cpu_deactivate(unsigned int cpu) int ret; set_cpu_active(cpu, false); + /* + * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU + * users of this state to go away such that all new such users will + * observe it. + * + * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might + * not imply sync_sched(), so wait for both. + * + * Do sync before park smpboot threads to take care the rcu boost case. + */ + if (IS_ENABLED(CONFIG_PREEMPT)) + synchronize_rcu_mult(call_rcu, call_rcu_sched); + else + synchronize_rcu(); if (!sched_smp_initialized) return 0;
