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Groups > linux.kernel > #1355066
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [patch 08/15] sched, hotplug: Move sync_rcu to be with set_cpu_active(false) |
| Date | 2016-03-10 13:10 +0100 |
| Message-ID | <rb7zJ-6OQ-23@gated-at.bofh.it> (permalink) |
| References | <rb7zI-6OQ-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Peter Zijlstra <peterz@infradead.org> 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) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/cpu.c | 15 --------------- kernel/sched/core.c | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 15 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -691,21 +691,6 @@ 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 hotplug thread */ kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7345,6 +7345,20 @@ int sched_cpu_deactivate(unsigned int cp 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;
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[patch 00/15] cpu/hotplug: Convert scheduler to hotplug state machine Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 14/15] sched/fair: Make ilb_notifier an explicit call Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 07/15] sched/hotplug: Convert cpu_[in]active notifiers to state machine Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 01/15] cpu/hotplug: Document states better Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 10/15] sched/migration: Move calc_load_migrate() into CPU_DYING Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 13/15] sched/hotplug: Make activate() the last hotplug step Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 05/15] sched: Consolidate the notifier maze Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 09/15] sched/migration: Move prepare transition to SCHED_STARTING state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 08/15] sched, hotplug: Move sync_rcu to be with set_cpu_active(false) Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 06/15] sched: Move sched_domains_numa_masks_clear() to DOWN_PREPARE Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 11/15] sched/migration: Move CPU_ONLINE into scheduler state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 03/15] sched: Make set_cpu_rq_start_time() a built in hotplug state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 12/15] sched/hotplug: Move migration CPU_DYING to sched_cpu_dying() Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 15/15] sched: Make hrtick_notifier an explicit call Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100 [patch 04/15] sched: Allow hotplug notifiers to be setup early Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:20 +0100
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