From: Abbas Raza <abbas_r...@mentor.com> wait_task_inactive shouldn't be called in kthread_bind for presmp initcalls the same way it is done in !SMP case.
more info here: http://permalink.gmane.org/gmane.linux.kernel.embedded/4046 This patch improves boot time for pre-smp initcalls as given below initcall spawn_ksoftirqd+0x0/0x54 returned 0 after 0 usecs initcall init_workqueues+0x0/0x358 returned 0 after 0 usecs initcall cpu_stop_init+0x0/0xcc returned 0 after 0 usecs boot time without this patch: initcall spawn_ksoftirqd+0x0/0x54 returned 0 after 9765 usecs initcall init_workqueues+0x0/0x358 returned 0 after 9765 usecs initcall cpu_stop_init+0x0/0xcc returned 0 after 19531 usecs Signed-off-by: Abbas Raza <abbas_r...@mentor.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Ingo Molnar <mi...@redhat.com> --- kernel/kthread.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index b579af5..80f19b5 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -221,10 +221,15 @@ EXPORT_SYMBOL(kthread_create_on_node); */ void kthread_bind(struct task_struct *p, unsigned int cpu) { - /* Must have done schedule() in kthread() before we set_task_cpu */ - if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) { - WARN_ON(1); - return; + if (!((num_online_cpus() == 1) && !cpu)) { + /* + * Must have done schedule() in kthread() before + * we set_task_cpu + */ + if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) { + WARN_ON(1); + return; + } } /* It's safe because the task is inactive. */ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
