On 05/13, Rafael J. Wysocki wrote:
>
> The suspend/hibernation is broken on SMP due to:
>
> commit 3540af8ffddcdbc7573451ac0b5cd57a2eaf8af5
> tifm: replace per-adapter kthread with freezeable workqueue
>
> Well, it looks like freezable worqueues still deadlock with CPU hotplug
> when worker threads are frozen.
Ugh. I thought we deprecated create_freezeable_workqueue(), exactly
because suspend was changed to call _cpu_down() after freeze().
It is not that "looks like freezable worqueues still deadlock", it
is "of course, freezable worqueues deadlocks" on CPU_DEAD.
The ->freezeable is still here just because of incoming "cpu-hotplug
using freezer" rework.
No?
> --- linux-2.6.22-rc1.orig/kernel/workqueue.c
> +++ linux-2.6.22-rc1/kernel/workqueue.c
> @@ -799,9 +799,7 @@ static int __devinit workqueue_cpu_callb
> struct cpu_workqueue_struct *cwq;
> struct workqueue_struct *wq;
>
> - action &= ~CPU_TASKS_FROZEN;
> -
> - switch (action) {
> + switch (action & ~CPU_TASKS_FROZEN) {
Confused. How can we see, say CPU_UP_PREPARE_FROZEN, if we cleared
CPU_TASKS_FROZEN bit?
> case CPU_LOCK_ACQUIRE:
> mutex_lock(&workqueue_mutex);
> return NOTIFY_OK;
> @@ -819,20 +817,29 @@ static int __devinit workqueue_cpu_callb
>
> switch (action) {
> case CPU_UP_PREPARE:
> + case CPU_UP_PREPARE_FROZEN:
> if (!create_workqueue_thread(cwq, cpu))
> break;
> printk(KERN_ERR "workqueue for %i failed\n", cpu);
> return NOTIFY_BAD;
>
> case CPU_ONLINE:
> + case CPU_ONLINE_FROZEN:
> start_workqueue_thread(cwq, cpu);
> break;
>
> case CPU_UP_CANCELED:
> + case CPU_UP_CANCELED_FROZEN:
> start_workqueue_thread(cwq, -1);
> case CPU_DEAD:
> cleanup_workqueue_thread(cwq, cpu);
> break;
> +
> + case CPU_DEAD_FROZEN:
> + if (wq->freezeable)
> + thaw_process(cwq->thread);
> + cleanup_workqueue_thread(cwq, cpu);
> + break;
> }
> }
Minor, but can't we do
...
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
start_workqueue_thread(cwq, -1);
case CPU_DEAD_FROZEN:
if (wq->freezeable)
// we can't see PF_FROZEN if it was
CPU_UP_CANCELED
thaw_process(cwq->thread);
case CPU_DEAD:
cleanup_workqueue_thread(cwq, cpu);
break;
?
Oleg.
-
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