8bb7844286
Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
336 lines
7.8 KiB
C
336 lines
7.8 KiB
C
/* CPU control.
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* (C) 2001, 2002, 2003, 2004 Rusty Russell
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*
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* This code is licenced under the GPL.
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*/
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#include <linux/proc_fs.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/notifier.h>
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#include <linux/sched.h>
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#include <linux/unistd.h>
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#include <linux/cpu.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/stop_machine.h>
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#include <linux/mutex.h>
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/* This protects CPUs going up and down... */
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static DEFINE_MUTEX(cpu_add_remove_lock);
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static DEFINE_MUTEX(cpu_bitmask_lock);
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static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
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/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
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* Should always be manipulated under cpu_add_remove_lock
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*/
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static int cpu_hotplug_disabled;
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#ifdef CONFIG_HOTPLUG_CPU
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/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
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static struct task_struct *recursive;
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static int recursive_depth;
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void lock_cpu_hotplug(void)
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{
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struct task_struct *tsk = current;
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if (tsk == recursive) {
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static int warnings = 10;
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if (warnings) {
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printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
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WARN_ON(1);
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warnings--;
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}
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recursive_depth++;
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return;
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}
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mutex_lock(&cpu_bitmask_lock);
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recursive = tsk;
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}
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EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
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void unlock_cpu_hotplug(void)
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{
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WARN_ON(recursive != current);
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if (recursive_depth) {
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recursive_depth--;
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return;
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}
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recursive = NULL;
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mutex_unlock(&cpu_bitmask_lock);
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}
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EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
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#endif /* CONFIG_HOTPLUG_CPU */
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/* Need to know about CPUs going up/down? */
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int __cpuinit register_cpu_notifier(struct notifier_block *nb)
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{
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int ret;
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mutex_lock(&cpu_add_remove_lock);
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ret = raw_notifier_chain_register(&cpu_chain, nb);
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mutex_unlock(&cpu_add_remove_lock);
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return ret;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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EXPORT_SYMBOL(register_cpu_notifier);
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void unregister_cpu_notifier(struct notifier_block *nb)
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{
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mutex_lock(&cpu_add_remove_lock);
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raw_notifier_chain_unregister(&cpu_chain, nb);
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mutex_unlock(&cpu_add_remove_lock);
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}
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EXPORT_SYMBOL(unregister_cpu_notifier);
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static inline void check_for_tasks(int cpu)
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{
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struct task_struct *p;
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write_lock_irq(&tasklist_lock);
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for_each_process(p) {
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if (task_cpu(p) == cpu &&
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(!cputime_eq(p->utime, cputime_zero) ||
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!cputime_eq(p->stime, cputime_zero)))
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printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
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(state = %ld, flags = %x) \n",
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p->comm, p->pid, cpu, p->state, p->flags);
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}
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write_unlock_irq(&tasklist_lock);
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}
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/* Take this CPU down. */
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static int take_cpu_down(void *unused)
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{
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int err;
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/* Ensure this CPU doesn't handle any more interrupts. */
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err = __cpu_disable();
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if (err < 0)
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return err;
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/* Force idle task to run as soon as we yield: it should
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immediately notice cpu is offline and die quickly. */
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sched_idle_next();
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return 0;
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}
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/* Requires cpu_add_remove_lock to be held */
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static int _cpu_down(unsigned int cpu, int tasks_frozen)
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{
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int err, nr_calls = 0;
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struct task_struct *p;
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cpumask_t old_allowed, tmp;
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void *hcpu = (void *)(long)cpu;
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unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
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if (num_online_cpus() == 1)
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return -EBUSY;
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if (!cpu_online(cpu))
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return -EINVAL;
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raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
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err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
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hcpu, -1, &nr_calls);
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if (err == NOTIFY_BAD) {
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__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
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hcpu, nr_calls, NULL);
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printk("%s: attempt to take down CPU %u failed\n",
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__FUNCTION__, cpu);
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err = -EINVAL;
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goto out_release;
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}
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/* Ensure that we are not runnable on dying cpu */
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old_allowed = current->cpus_allowed;
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tmp = CPU_MASK_ALL;
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cpu_clear(cpu, tmp);
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set_cpus_allowed(current, tmp);
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mutex_lock(&cpu_bitmask_lock);
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p = __stop_machine_run(take_cpu_down, NULL, cpu);
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mutex_unlock(&cpu_bitmask_lock);
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if (IS_ERR(p) || cpu_online(cpu)) {
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/* CPU didn't die: tell everyone. Can't complain. */
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if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
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hcpu) == NOTIFY_BAD)
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BUG();
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if (IS_ERR(p)) {
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err = PTR_ERR(p);
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goto out_allowed;
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}
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goto out_thread;
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}
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/* Wait for it to sleep (leaving idle task). */
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while (!idle_cpu(cpu))
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yield();
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/* This actually kills the CPU. */
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__cpu_die(cpu);
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/* CPU is completely dead: tell everyone. Too late to complain. */
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if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
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hcpu) == NOTIFY_BAD)
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BUG();
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check_for_tasks(cpu);
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out_thread:
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err = kthread_stop(p);
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out_allowed:
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set_cpus_allowed(current, old_allowed);
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out_release:
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raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
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return err;
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}
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int cpu_down(unsigned int cpu)
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{
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int err = 0;
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mutex_lock(&cpu_add_remove_lock);
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if (cpu_hotplug_disabled)
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err = -EBUSY;
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else
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err = _cpu_down(cpu, 0);
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mutex_unlock(&cpu_add_remove_lock);
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return err;
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}
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#endif /*CONFIG_HOTPLUG_CPU*/
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/* Requires cpu_add_remove_lock to be held */
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static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
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{
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int ret, nr_calls = 0;
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void *hcpu = (void *)(long)cpu;
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unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
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if (cpu_online(cpu) || !cpu_present(cpu))
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return -EINVAL;
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raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
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ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
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-1, &nr_calls);
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if (ret == NOTIFY_BAD) {
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printk("%s: attempt to bring up CPU %u failed\n",
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__FUNCTION__, cpu);
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ret = -EINVAL;
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goto out_notify;
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}
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/* Arch-specific enabling code. */
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mutex_lock(&cpu_bitmask_lock);
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ret = __cpu_up(cpu);
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mutex_unlock(&cpu_bitmask_lock);
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if (ret != 0)
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goto out_notify;
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BUG_ON(!cpu_online(cpu));
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/* Now call notifier in preparation. */
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raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
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out_notify:
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if (ret != 0)
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__raw_notifier_call_chain(&cpu_chain,
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CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
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raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
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return ret;
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}
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int __cpuinit cpu_up(unsigned int cpu)
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{
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int err = 0;
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mutex_lock(&cpu_add_remove_lock);
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if (cpu_hotplug_disabled)
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err = -EBUSY;
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else
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err = _cpu_up(cpu, 0);
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mutex_unlock(&cpu_add_remove_lock);
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return err;
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}
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#ifdef CONFIG_SUSPEND_SMP
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/* Needed to prevent the microcode driver from requesting firmware in its CPU
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* hotplug notifier during the suspend/resume.
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*/
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int suspend_cpu_hotplug;
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EXPORT_SYMBOL(suspend_cpu_hotplug);
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static cpumask_t frozen_cpus;
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int disable_nonboot_cpus(void)
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{
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int cpu, first_cpu, error = 0;
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mutex_lock(&cpu_add_remove_lock);
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suspend_cpu_hotplug = 1;
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first_cpu = first_cpu(cpu_online_map);
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/* We take down all of the non-boot CPUs in one shot to avoid races
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* with the userspace trying to use the CPU hotplug at the same time
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*/
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cpus_clear(frozen_cpus);
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printk("Disabling non-boot CPUs ...\n");
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for_each_online_cpu(cpu) {
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if (cpu == first_cpu)
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continue;
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error = _cpu_down(cpu, 1);
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if (!error) {
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cpu_set(cpu, frozen_cpus);
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printk("CPU%d is down\n", cpu);
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} else {
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printk(KERN_ERR "Error taking CPU%d down: %d\n",
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cpu, error);
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break;
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}
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}
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if (!error) {
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BUG_ON(num_online_cpus() > 1);
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/* Make sure the CPUs won't be enabled by someone else */
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cpu_hotplug_disabled = 1;
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} else {
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printk(KERN_ERR "Non-boot CPUs are not disabled\n");
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}
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suspend_cpu_hotplug = 0;
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mutex_unlock(&cpu_add_remove_lock);
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return error;
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}
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void enable_nonboot_cpus(void)
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{
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int cpu, error;
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/* Allow everyone to use the CPU hotplug again */
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mutex_lock(&cpu_add_remove_lock);
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cpu_hotplug_disabled = 0;
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if (cpus_empty(frozen_cpus))
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goto out;
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suspend_cpu_hotplug = 1;
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printk("Enabling non-boot CPUs ...\n");
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for_each_cpu_mask(cpu, frozen_cpus) {
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error = _cpu_up(cpu, 1);
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if (!error) {
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printk("CPU%d is up\n", cpu);
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continue;
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}
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printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
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}
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cpus_clear(frozen_cpus);
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suspend_cpu_hotplug = 0;
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out:
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mutex_unlock(&cpu_add_remove_lock);
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}
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#endif
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