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Commit fc75cdfa authored by Heiko Carstens's avatar Heiko Carstens Committed by Linus Torvalds
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[PATCH] cpu hotplug: fix CPU_UP_CANCEL handling 



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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 04a3446c

kernel/sched.c

+2 −0
Original line number Diff line number Diff line
@@ -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));

kernel/softirq.c

+2 −0
Original line number Diff line number Diff line
@@ -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));

kernel/softlockup.c

+2 −0
Original line number Diff line number Diff line
@@ -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));

kernel/workqueue.c

+2 −0
Original line number Diff line number Diff line
@@ -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));