From 984581728eb4b2e10baed3d606f85a119795b207 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 26 Feb 2016 18:43:25 +0000 Subject: [PATCH] cpu/hotplug: Split out cpu down functions Split cpu_down in separate functions in preparation for state machine conversion. Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: Rik van Riel Cc: Rafael Wysocki Cc: "Srivatsa S. Bhat" Cc: Peter Zijlstra Cc: Arjan van de Ven Cc: Sebastian Siewior Cc: Rusty Russell Cc: Steven Rostedt Cc: Oleg Nesterov Cc: Tejun Heo Cc: Andrew Morton Cc: Paul McKenney Cc: Linus Torvalds Cc: Paul Turner Link: http://lkml.kernel.org/r/20160226182340.511796562@linutronix.de Signed-off-by: Thomas Gleixner --- kernel/cpu.c | 83 +++++++++++++++++++++++++++++++++------------------- 1 file changed, 53 insertions(+), 30 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 15a413639abc..0b5d2596f3ec 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -266,11 +266,6 @@ static int bringup_cpu(unsigned int cpu) } #ifdef CONFIG_HOTPLUG_CPU - -static void cpu_notify_nofail(unsigned long val, unsigned int cpu) -{ - BUG_ON(cpu_notify(val, cpu)); -} EXPORT_SYMBOL(register_cpu_notifier); EXPORT_SYMBOL(__register_cpu_notifier); @@ -353,6 +348,25 @@ static inline void check_for_tasks(int dead_cpu) read_unlock(&tasklist_lock); } +static void cpu_notify_nofail(unsigned long val, unsigned int cpu) +{ + BUG_ON(cpu_notify(val, cpu)); +} + +static int notify_down_prepare(unsigned int cpu) +{ + int err, nr_calls = 0; + + err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); + if (err) { + nr_calls--; + __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); + pr_warn("%s: attempt to take down CPU %u failed\n", + __func__, cpu); + } + return err; +} + /* Take this CPU down. */ static int take_cpu_down(void *_param) { @@ -371,29 +385,9 @@ static int take_cpu_down(void *_param) return 0; } -/* Requires cpu_add_remove_lock to be held */ -static int _cpu_down(unsigned int cpu, int tasks_frozen) +static int takedown_cpu(unsigned int cpu) { - int err, nr_calls = 0; - - if (num_online_cpus() == 1) - return -EBUSY; - - if (!cpu_online(cpu)) - return -EINVAL; - - cpu_hotplug_begin(); - - cpuhp_tasks_frozen = tasks_frozen; - - err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); - if (err) { - nr_calls--; - __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); - pr_warn("%s: attempt to take down CPU %u failed\n", - __func__, cpu); - goto out_release; - } + int err; /* * By now we've cleared cpu_active_mask, wait for all preempt-disabled @@ -426,7 +420,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) /* CPU didn't die: tell everyone. Can't complain. */ cpu_notify_nofail(CPU_DOWN_FAILED, cpu); irq_unlock_sparse(); - goto out_release; + return err; } BUG_ON(cpu_online(cpu)); @@ -449,11 +443,40 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) /* This actually kills the CPU. */ __cpu_die(cpu); - /* CPU is completely dead: tell everyone. Too late to complain. */ tick_cleanup_dead_cpu(cpu); - cpu_notify_nofail(CPU_DEAD, cpu); + return 0; +} +static int notify_dead(unsigned int cpu) +{ + cpu_notify_nofail(CPU_DEAD, cpu); check_for_tasks(cpu); + return 0; +} + +/* Requires cpu_add_remove_lock to be held */ +static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) +{ + int err; + + if (num_online_cpus() == 1) + return -EBUSY; + + if (!cpu_online(cpu)) + return -EINVAL; + + cpu_hotplug_begin(); + + cpuhp_tasks_frozen = tasks_frozen; + + err = notify_down_prepare(cpu); + if (err) + goto out_release; + err = takedown_cpu(cpu); + if (err) + goto out_release; + + notify_dead(cpu); out_release: cpu_hotplug_done(); -- 2.39.5