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Commit 7d7e499f authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent 211b0cdc

include/linux/smpboot.h

+5 −0
Original line number Diff line number Diff line
@@ -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;

};

kernel/smpboot.c

+3 −2
Original line number Diff line number Diff line
@@ -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);

}