kernel_optimize_test/drivers/xen/cpu_hotplug.c
Konrad Rzeszutek Wilk 5b02aa1e6e xen/bootup: During bootup suppress XENBUS: Unable to read cpu state
When the initial domain starts, it prints (depending on the
amount of CPUs) a slew of
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state

which provide no useful information - as the error is a valid
issue - but not on the initial domain. The reason is that the
XenStore is not accessible at that time (it is after all the
first guest) so the CPU hotplug watch cannot parse "availability/cpu"
attribute.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-02-03 16:05:30 -05:00

113 lines
2.0 KiB
C

#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))
arch_register_cpu(cpu);
set_cpu_present(cpu, true);
}
static void disable_hotplug_cpu(int cpu)
{
if (cpu_present(cpu))
arch_unregister_cpu(cpu);
set_cpu_present(cpu, false);
}
static int vcpu_online(unsigned int cpu)
{
int err;
char dir[32], state[32];
sprintf(dir, "cpu/%u", cpu);
err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state);
if (err != 1) {
if (!xen_initial_domain())
printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
return err;
}
if (strcmp(state, "online") == 0)
return 1;
else if (strcmp(state, "offline") == 0)
return 0;
printk(KERN_ERR "XENBUS: 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:
(void)cpu_down(cpu);
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 };
if (!xen_pv_domain())
return -ENODEV;
register_xenstore_notifier(&xsn_cpu);
return 0;
}
arch_initcall(setup_vcpu_hotplug_event);