On Thu, Dec 21, 2017 at 01:44:48PM -0200, Jose Ricardo Ziviani wrote: > The hotplug engine uses its own workqueue to handle IRQ requests, the > problem is that such workqueue is initialized not so early in the boot > process. > > Thus, when the kernel is ready to handle IRQ requests, after the system > workqueue is initialized, we have a timeframe where any hotplug issued > by the client will result in a kernel panic. That timeframe goes until > the hotplug workqueue is initialized. > > It would be good to have the hotplug workqueue initialized as soon as > the system workqueue but I don't think it is possible. So, this patch > uses the system workqueue as a fallback the handle such IRQs. > > Signed-off-by: Jose Ricardo Ziviani <jos...@linux.vnet.ibm.com>
I don't think this is the right approach.
It seems to me the bug is that the hotplug interrupt is registered in
init_ras_IRQ(), before the work queue is initialized in
pseries_dlpar_init(). We need to correct that ordering.
> ---
> arch/powerpc/platforms/pseries/dlpar.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/dlpar.c
> b/arch/powerpc/platforms/pseries/dlpar.c
> index 6e35780c5962..0474aa14b5f6 100644
> --- a/arch/powerpc/platforms/pseries/dlpar.c
> +++ b/arch/powerpc/platforms/pseries/dlpar.c
> @@ -399,7 +399,15 @@ void queue_hotplug_event(struct pseries_hp_errorlog
> *hp_errlog,
> work->errlog = hp_errlog_copy;
> work->hp_completion = hotplug_done;
> work->rc = rc;
> - queue_work(pseries_hp_wq, (struct work_struct *)work);
> +
> + /* The hotplug workqueue may happen to be NULL at the moment
> + * this code is executed, during the boot phase. So, in this
> + * scenario, we can fallback to the system workqueue.
> + */
> + if (unlikely(pseries_hp_wq == NULL))
> + schedule_work((struct work_struct *)work);
> + else
> + queue_work(pseries_hp_wq, (struct work_struct *)work);
> } else {
> *rc = -ENOMEM;
> kfree(hp_errlog_copy);
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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