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[PATCH] cpu hotplug: fix CPU_UP_CANCEL handling

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If a cpu hotplug callback fails on CPU_UP_PREPARE, all callbacks will be
called with CPU_UP_CANCELED.  A few of these callbacks assume that on
CPU_UP_PREPARE a pointer to task has been stored in a percpu array.  This
assumption is not true if CPU_UP_PREPARE fails and the following calls to
kthread_bind() in CPU_UP_CANCELED will cause an addressing exception
because of passing a NULL pointer.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Heiko Carstens 2006-06-25 05:49:10 -07:00 committed by Linus Torvalds
parent 04a3446c90
commit fc75cdfa5b
4 changed files with 8 additions and 0 deletions
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2
kernel/sched.c
View file

@ -4756,6 +4756,8 @@ static int migration_call(struct notifier_block *nfb, unsigned long action,
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
if (!cpu_rq(cpu)->migration_thread)
break;
/* Unbind it from offline cpu so it can run. Fall thru. */
kthread_bind(cpu_rq(cpu)->migration_thread,
any_online_cpu(cpu_online_map));

2
kernel/softirq.c
View file

@ -470,6 +470,8 @@ static int cpu_callback(struct notifier_block *nfb,
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
if (!per_cpu(ksoftirqd, hotcpu))
break;
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(ksoftirqd, hotcpu),
any_online_cpu(cpu_online_map));

2
kernel/softlockup.c
View file

@ -127,6 +127,8 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
if (!per_cpu(watchdog_task, hotcpu))
break;
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(watchdog_task, hotcpu),
any_online_cpu(cpu_online_map));

2
kernel/workqueue.c
View file

@ -590,6 +590,8 @@ static int workqueue_cpu_callback(struct notifier_block *nfb,
case CPU_UP_CANCELED:
list_for_each_entry(wq, &workqueues, list) {
if (!per_cpu_ptr(wq->cpu_wq, hotcpu)->thread)
continue;
/* Unbind so it can run. */
kthread_bind(per_cpu_ptr(wq->cpu_wq, hotcpu)->thread,
any_online_cpu(cpu_online_map));