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[PATCH] cpu hoptlug: avoid usage of smp_processor_id() in preemptible code 

Replace smp_processor_id() with any_online_cpu(cpu_online_map) in order to
avoid lots of "BUG: using smp_processor_id() in preemptible [00000001]
code:..." messages in case taking a cpu online fails.

All the traces start at the last notifier_call_chain(...) in kernel/cpu.c.
Since we hold the cpu_control semaphore it shouldn't be any problem to access
cpu_online_map.

The reason why cpu_up failed is simply that the cpu that was supposed to be
taken online wasn't even there.  That is because on s390 we never know when a
new cpu comes and therefore cpu_possible_map consists of only ones and doesn't
reflect reality.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
hifive-unleashed-5.1
Heiko Carstens 2005-11-07 00:58:38 -08:00 committed by Linus Torvalds
parent cc658cfe3c
commit a4c4af7c8d
4 changed files with 7 additions and 4 deletions
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3
kernel/sched.c
View File

@ -4680,7 +4680,8 @@ static int migration_call(struct notifier_block *nfb, unsigned long action,
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
/* Unbind it from offline cpu so it can run. Fall thru. */
kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
kthread_bind(cpu_rq(cpu)->migration_thread,
any_online_cpu(cpu_online_map));
kthread_stop(cpu_rq(cpu)->migration_thread);
cpu_rq(cpu)->migration_thread = NULL;
break;

3
kernel/softirq.c
View File

@ -470,7 +470,8 @@ static int __devinit cpu_callback(struct notifier_block *nfb,
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(ksoftirqd, hotcpu), smp_processor_id());
kthread_bind(per_cpu(ksoftirqd, hotcpu),
any_online_cpu(cpu_online_map));
case CPU_DEAD:
p = per_cpu(ksoftirqd, hotcpu);
per_cpu(ksoftirqd, hotcpu) = NULL;

3
kernel/softlockup.c
View File

@ -123,7 +123,8 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(watchdog_task, hotcpu), smp_processor_id());
kthread_bind(per_cpu(watchdog_task, hotcpu),
any_online_cpu(cpu_online_map));
case CPU_DEAD:
p = per_cpu(watchdog_task, hotcpu);
per_cpu(watchdog_task, hotcpu) = NULL;

2
kernel/workqueue.c
View File

@ -524,7 +524,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
list_for_each_entry(wq, &workqueues, list) {
/* Unbind so it can run. */
kthread_bind(per_cpu_ptr(wq->cpu_wq, hotcpu)->thread,
smp_processor_id());
any_online_cpu(cpu_online_map));
cleanup_workqueue_thread(wq, hotcpu);
}
break;