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 <t...@linutronix.de>
---
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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