From 7d7e499f7333f68b7e7f67d14b9c1480913b4afb Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 31 Jan 2013 12:11:12 +0000 Subject: [PATCH] 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 Cc: Peter Zijlstra Cc: Rusty Russell Cc: Paul McKenney Cc: Srivatsa S. Bhat Cc: Arjan van de Veen Cc: Paul Turner Cc: Richard Weinberger Cc: Magnus Damm Link: http://lkml.kernel.org/r/20130131120741.553993267@linutronix.de Signed-off-by: Thomas Gleixner --- include/linux/smpboot.h | 5 +++++ kernel/smpboot.c | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h index e0106d8581d3..c65dee059913 100644 --- a/include/linux/smpboot.h +++ b/include/linux/smpboot.h @@ -14,6 +14,8 @@ struct smpboot_thread_data; * @thread_should_run: Check whether the thread should run or not. Called with * preemption disabled. * @thread_fn: The associated thread function + * @create: Optional setup function, called when the thread gets + * created (Not called from the thread context) * @setup: Optional setup function, called when the thread gets * operational the first time * @cleanup: Optional cleanup function, called when the thread @@ -22,6 +24,7 @@ struct smpboot_thread_data; * parked (cpu offline) * @unpark: Optional unpark function, called when the thread is * unparked (cpu online) + * @selfparking: Thread is not parked by the park function. * @thread_comm: The base name of the thread */ struct smp_hotplug_thread { @@ -29,10 +32,12 @@ struct smp_hotplug_thread { struct list_head list; int (*thread_should_run)(unsigned int cpu); void (*thread_fn)(unsigned int cpu); + void (*create)(unsigned int cpu); void (*setup)(unsigned int cpu); void (*cleanup)(unsigned int cpu, bool online); void (*park)(unsigned int cpu); void (*unpark)(unsigned int cpu); + bool selfparking; const char *thread_comm; }; 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); }