2016-03-11 09:01:33

by Anna-Maria Behnsen

Subject: [PATCH] xen/events/fifo: Add missing hotplug notifier transition

The evtchn_fifo_cpu_notification() hotplug callback lacks handling of
the CPU_UP_CANCELED case. That means, if CPU_UP_PREPARE fails, the
handle of the fifo events is not dropped.

Add handling for CPU_UP_CANCELED transition to drop the fifo events
handle.

Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: David Vrabel <[email protected]>
Cc: [email protected]
Signed-off-by: Anna-Maria Gleixner <[email protected]>
---
drivers/xen/events/events_fifo.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -432,6 +432,7 @@ static int evtchn_fifo_cpu_notification(
ret = evtchn_fifo_alloc_control_block(cpu);
break;
case CPU_DEAD:
+ case CPU_UP_CANCELED:
__evtchn_fifo_handle_events(cpu, true);
break;
default:

2016-03-11 10:54:03

by David Vrabel

Subject: Re: [Xen-devel] [PATCH] xen/events/fifo: Add missing hotplug notifier transition

On 11/03/16 09:00, Anna-Maria Gleixner wrote:
> The evtchn_fifo_cpu_notification() hotplug callback lacks handling of
> the CPU_UP_CANCELED case. That means, if CPU_UP_PREPARE fails, the
> handle of the fifo events is not dropped.
>
> Add handling for CPU_UP_CANCELED transition to drop the fifo events
> handle.

__evtchn_fifo_handle_events() does not releases resources, it processes
any pending events for this CPU.

This patch would only be necessary if a CPU in CPU_UP_CANCELED state may
have had unmasked interrupts. If so you would need:


case CPU_UP_CANCELED:
if (per_cpu(cpu_control_block, cpu))
__evtchn_fifo_handle_events(cpu, true);
break;

To handle the case where the control block allocation or initialization
failed during CPU_UP_PREPARE.

David

>
> Cc: Konrad Rzeszutek Wilk <[email protected]>
> Cc: Boris Ostrovsky <[email protected]>
> Cc: David Vrabel <[email protected]>
> Cc: [email protected]
> Signed-off-by: Anna-Maria Gleixner <[email protected]>
> ---
> drivers/xen/events/events_fifo.c | 1 +
> 1 file changed, 1 insertion(+)
>
> --- a/drivers/xen/events/events_fifo.c
> +++ b/drivers/xen/events/events_fifo.c
> @@ -432,6 +432,7 @@ static int evtchn_fifo_cpu_notification(
> ret = evtchn_fifo_alloc_control_block(cpu);
> break;
> case CPU_DEAD:
> + case CPU_UP_CANCELED:
> __evtchn_fifo_handle_events(cpu, true);
> break;
> default:
>
> _______________________________________________
> Xen-devel mailing list
> [email protected]
> http://lists.xen.org/xen-devel
>

2016-03-11 11:26:18

by Anna-Maria Behnsen

Subject: Re: [Xen-devel] [PATCH] xen/events/fifo: Add missing hotplug notifier transition

On Fri, 11 Mar 2016, David Vrabel wrote:

> On 11/03/16 09:00, Anna-Maria Gleixner wrote:
> > The evtchn_fifo_cpu_notification() hotplug callback lacks handling of
> > the CPU_UP_CANCELED case. That means, if CPU_UP_PREPARE fails, the
> > handle of the fifo events is not dropped.
> >
> > Add handling for CPU_UP_CANCELED transition to drop the fifo events
> > handle.
>
> __evtchn_fifo_handle_events() does not releases resources, it processes
> any pending events for this CPU.
>
> This patch would only be necessary if a CPU in CPU_UP_CANCELED state may
> have had unmasked interrupts. If so you would need:

Thanks for the explanation

> case CPU_UP_CANCELED:
> if (per_cpu(cpu_control_block, cpu))
> __evtchn_fifo_handle_events(cpu, true);
> break;
>
> To handle the case where the control block allocation or initialization
> failed during CPU_UP_PREPARE.

This would not be necessary, because if the CPU_UP_PREPARE of this
notifier fails, the CPU_UP_CANCELLED of this notifier will not be
invoked.

Anna-Maria