[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: 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>
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 336f92d..9e2f1c6 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -470,6 +470,8 @@
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));