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    SubjectRe: [patch 01/40] smpboot: Allow selfparking per cpu threads
    On Thu, Jan 31, 2013 at 12:11:12PM -0000, Thomas Gleixner wrote:
    > 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>

    Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

    > ---
    > include/linux/smpboot.h | 5 +++++
    > kernel/smpboot.c | 5 +++--
    > 2 files changed, 8 insertions(+), 2 deletions(-)
    >
    > Index: linux-2.6/include/linux/smpboot.h
    > ===================================================================
    > --- linux-2.6.orig/include/linux/smpboot.h
    > +++ linux-2.6/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;
    > };
    >
    > Index: linux-2.6/kernel/smpboot.c
    > ===================================================================
    > --- linux-2.6.orig/kernel/smpboot.c
    > +++ linux-2.6/kernel/smpboot.c
    > @@ -183,9 +183,10 @@ __smpboot_create_thread(struct smp_hotpl
    > 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 s
    > {
    > struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
    >
    > - if (tsk)
    > + if (tsk && !ht->selfparking)
    > kthread_park(tsk);
    > }
    >
    >
    >



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