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Subject[PATCH 2/2] xen/events: Convert to hotplug state machine
Date
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
Changes from Sebastian's original version:
* Renamed hotplug state from CPUHP_XEN_EV_PREPEARE to CPUHP_XEN_EVTCHN_PREPARE
* Dropped suggestion in the commit messages about moving evtchn_fifo_alloc_control_block
call since I think it is in the right place right now.


drivers/xen/events/events_fifo.c | 34 ++++++++++++----------------------
include/linux/cpuhotplug.h | 1 +
2 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 266c2c7..7ef27c6 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -418,30 +418,18 @@ static int evtchn_fifo_alloc_control_block(unsigned cpu)
return ret;
}

-static int evtchn_fifo_cpu_notification(struct notifier_block *self,
- unsigned long action,
- void *hcpu)
+static int xen_evtchn_cpu_prepare(unsigned int cpu)
{
- int cpu = (long)hcpu;
- int ret = 0;
-
- switch (action) {
- case CPU_UP_PREPARE:
- if (!per_cpu(cpu_control_block, cpu))
- ret = evtchn_fifo_alloc_control_block(cpu);
- break;
- case CPU_DEAD:
- __evtchn_fifo_handle_events(cpu, true);
- break;
- default:
- break;
- }
- return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
+ if (!per_cpu(cpu_control_block, cpu))
+ return evtchn_fifo_alloc_control_block(cpu);
+ return 0;
}

-static struct notifier_block evtchn_fifo_cpu_notifier = {
- .notifier_call = evtchn_fifo_cpu_notification,
-};
+static int xen_evtchn_cpu_dead(unsigned int cpu)
+{
+ __evtchn_fifo_handle_events(cpu, true);
+ return 0;
+}

int __init xen_evtchn_fifo_init(void)
{
@@ -456,7 +444,9 @@ int __init xen_evtchn_fifo_init(void)

evtchn_ops = &evtchn_ops_fifo;

- register_cpu_notifier(&evtchn_fifo_cpu_notifier);
+ cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
+ "CPUHP_XEN_EVTCHN_PREPARE",
+ xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
out:
put_cpu();
return ret;
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index d6beeb9..c60a17c 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -22,6 +22,7 @@ enum cpuhp_state {
CPUHP_SMPCFD_PREPARE,
CPUHP_RCUTREE_PREP,
CPUHP_XEN_PREPARE,
+ CPUHP_XEN_EVTCHN_PREPARE,
CPUHP_NOTIFY_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_BRINGUP_CPU,
--
1.7.1
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