smpboot: Allow selfparking per cpu threads

The stop machine threads are still killed when a cpu goes offline. The
reason is that the thread is used to bring the cpu down, so it can't
be parked along with the other per cpu threads.

Allow a per cpu thread to be excluded from automatic parking, so it
can park itself once it's done

Add a create callback function as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Weinberger <rw@linutronix.de>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130131120741.553993267@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index d6c5fc054242..d4abac261779 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -183,9 +183,10 @@ __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
                 kfree(td);
                 return PTR_ERR(tsk);
         }
-
         get_task_struct(tsk);
         *per_cpu_ptr(ht->store, cpu) = tsk;
+        if (ht->create)
+                ht->create(cpu);
         return 0;
 }
 
@@ -225,7 +226,7 @@ static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
 {
         struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
 
-        if (tsk)
+        if (tsk && !ht->selfparking)
                 kthread_park(tsk);
 }