On Thu, Apr 26, 2007 at 02:15:47PM +0400, Oleg Nesterov wrote: > > I can't understand why do we need to re-bind this thread. We are doing > kthread_stop()->wake_up() below, at this point move_task_off_dead_cpu() > has already cared about this task, no? > > > We only need to ensure in kthread_bind that the task which is being > > bound is not running or exiting. Doesn't matter if it's sleeping in > > TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE state. > > We need to ensure that this task can't be woken after return from > wait_task_inactive(k), otherwise set_task_cpu() after that is not safe. > > TASK_INTERRUPTIBLE doesn't protect us from freezing. > > Couldn't we just remove this kthread_bind() ?
Fair enough. We are anyway kthread_stop()ping other per-cpu kernel threads after move_task_off_dead_cpu(), so we can do it with the stop_machine_run thread as well. I just checked with Vatsa if there was any subtle reason why they had put in the kthread_bind() in cpu.c. Vatsa cannot seem to recollect any and I can't see any. So let us just remove the kthread_bind. Signed-off-by: Gautham R Shenoy <[EMAIL PROTECTED]> --- kernel/cpu.c | 4 ---- 1 files changed, 4 deletions(-) Index: linux-2.6.21-rc7/kernel/cpu.c =================================================================== --- linux-2.6.21-rc7.orig/kernel/cpu.c +++ linux-2.6.21-rc7/kernel/cpu.c @@ -176,10 +176,6 @@ static int _cpu_down(unsigned int cpu, i /* This actually kills the CPU. */ __cpu_die(cpu); - /* Move it here so it can run. */ - kthread_bind(p, get_cpu()); - put_cpu(); - /* CPU is completely dead: tell everyone. Too late to complain. */ if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod, hcpu) == NOTIFY_BAD) -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!" - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/