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linux-next/drivers/xen/cpu_hotplug.c
Stefano Stabellini 1c7a62137b xen, cpu_hotplug: call device_offline instead of cpu_down
When offlining a cpu, instead of cpu_down, call device_offline, which
also takes care of updating the cpu.dev.offline field. This keeps the
sysfs file /sys/devices/system/cpu/cpuN/online, up to date.  Also move
the call to disable_hotplug_cpu, because it makes more sense to have it
there.

We don't call device_online at cpu-hotplug time, because that would
immediately take the cpu online, while we want to retain the current
behaviour: the user needs to explicitly enable the cpu after it has
been hotplugged.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: konrad.wilk@oracle.com
CC: boris.ostrovsky@oracle.com
CC: david.vrabel@citrix.com
2015-10-23 14:20:48 +01:00

123 lines
2.2 KiB
C

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
#include <linux/notifier.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
#include <asm/xen/hypervisor.h>
#include <asm/cpu.h>
static void enable_hotplug_cpu(int cpu)
{
if (!cpu_present(cpu))
xen_arch_register_cpu(cpu);
set_cpu_present(cpu, true);
}
static void disable_hotplug_cpu(int cpu)
{
if (cpu_online(cpu)) {
lock_device_hotplug();
device_offline(get_cpu_device(cpu));
unlock_device_hotplug();
}
if (cpu_present(cpu))
xen_arch_unregister_cpu(cpu);
set_cpu_present(cpu, false);
}
static int vcpu_online(unsigned int cpu)
{
int err;
char dir[16], state[16];
sprintf(dir, "cpu/%u", cpu);
err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
if (err != 1) {
if (!xen_initial_domain())
pr_err("Unable to read cpu state\n");
return err;
}
if (strcmp(state, "online") == 0)
return 1;
else if (strcmp(state, "offline") == 0)
return 0;
pr_err("unknown state(%s) on CPU%d\n", state, cpu);
return -EINVAL;
}
static void vcpu_hotplug(unsigned int cpu)
{
if (!cpu_possible(cpu))
return;
switch (vcpu_online(cpu)) {
case 1:
enable_hotplug_cpu(cpu);
break;
case 0:
disable_hotplug_cpu(cpu);
break;
default:
break;
}
}
static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
unsigned int cpu;
char *cpustr;
const char *node = vec[XS_WATCH_PATH];
cpustr = strstr(node, "cpu/");
if (cpustr != NULL) {
sscanf(cpustr, "cpu/%u", &cpu);
vcpu_hotplug(cpu);
}
}
static int setup_cpu_watcher(struct notifier_block *notifier,
unsigned long event, void *data)
{
int cpu;
static struct xenbus_watch cpu_watch = {
.node = "cpu",
.callback = handle_vcpu_hotplug_event};
(void)register_xenbus_watch(&cpu_watch);
for_each_possible_cpu(cpu) {
if (vcpu_online(cpu) == 0) {
(void)cpu_down(cpu);
set_cpu_present(cpu, false);
}
}
return NOTIFY_DONE;
}
static int __init setup_vcpu_hotplug_event(void)
{
static struct notifier_block xsn_cpu = {
.notifier_call = setup_cpu_watcher };
#ifdef CONFIG_X86
if (!xen_pv_domain())
#else
if (!xen_domain())
#endif
return -ENODEV;
register_xenstore_notifier(&xsn_cpu);
return 0;
}
arch_initcall(setup_vcpu_hotplug_event);