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oprofile/x86: protect cpu hotplug sections 

This patch reworks oprofile cpu hotplug code as follows:

Introduce ctr_running variable to check, if counters are running or
not. The state must be known for taking a cpu on or offline and when
switching counters during counter multiplexing.

Protect on_each_cpu() sections with get_online_cpus()/put_online_cpu()
functions. This is necessary if notifiers or states are
modified. Within these sections the cpu mask may not change.

Switch only between counters in nmi_cpu_switch(), if counters are
running. Otherwise the switch may restart a counter though they are
disabled.

Add nmi_cpu_setup() and nmi_cpu_shutdown() to cpu hotplug code. The
function must also be called to avoid uninitialzed counter usage.

Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Robert Richter <robert.richter@amd.com>
This commit is contained in:
Robert Richter 2010-04-29 14:55:55 +02:00
parent 216f3d9b4e
commit 6ae56b55bc
1 changed files with 46 additions and 6 deletions
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52
arch/x86/oprofile/nmi_int.c
View File

@ -31,8 +31,9 @@ static struct op_x86_model_spec *model;
static DEFINE_PER_CPU(struct op_msrs, cpu_msrs);
static DEFINE_PER_CPU(unsigned long, saved_lvtpc);
/* 0 == registered but off, 1 == registered and on */
static int nmi_enabled = 0;
/* must be protected with get_online_cpus()/put_online_cpus(): */
static int nmi_enabled;
static int ctr_running;
struct op_counter_config counter_config[OP_MAX_COUNTER];
@ -103,7 +104,10 @@ static void nmi_cpu_start(void *dummy)
static int nmi_start(void)
{
get_online_cpus();
on_each_cpu(nmi_cpu_start, NULL, 1);
ctr_running = 1;
put_online_cpus();
return 0;
}
@ -118,7 +122,10 @@ static void nmi_cpu_stop(void *dummy)
static void nmi_stop(void)
{
get_online_cpus();
on_each_cpu(nmi_cpu_stop, NULL, 1);
ctr_running = 0;
put_online_cpus();
}
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
@ -258,7 +265,10 @@ static int nmi_switch_event(void)
if (nmi_multiplex_on() < 0)
return -EINVAL; /* not necessary */
on_each_cpu(nmi_cpu_switch, NULL, 1);
get_online_cpus();
if (ctr_running)
on_each_cpu(nmi_cpu_switch, NULL, 1);
put_online_cpus();
return 0;
}
@ -386,8 +396,11 @@ static int nmi_setup(void)
if (err)
goto fail;
get_online_cpus();
on_each_cpu(nmi_cpu_setup, NULL, 1);
nmi_enabled = 1;
put_online_cpus();
return 0;
fail:
free_msrs();
@ -433,8 +446,11 @@ static void nmi_shutdown(void)
{
struct op_msrs *msrs;
nmi_enabled = 0;
get_online_cpus();
on_each_cpu(nmi_cpu_shutdown, NULL, 1);
nmi_enabled = 0;
ctr_running = 0;
put_online_cpus();
unregister_die_notifier(&profile_exceptions_nb);
msrs = &get_cpu_var(cpu_msrs);
model->shutdown(msrs);
@ -442,6 +458,22 @@ static void nmi_shutdown(void)
put_cpu_var(cpu_msrs);
}
static void nmi_cpu_up(void *dummy)
{
if (nmi_enabled)
nmi_cpu_setup(dummy);
if (ctr_running)
nmi_cpu_start(dummy);
}
static void nmi_cpu_down(void *dummy)
{
if (ctr_running)
nmi_cpu_stop(dummy);
if (nmi_enabled)
nmi_cpu_shutdown(dummy);
}
static int nmi_create_files(struct super_block *sb, struct dentry *root)
{
unsigned int i;
@ -478,10 +510,10 @@ static int oprofile_cpu_notifier(struct notifier_block *b, unsigned long action,
switch (action) {
case CPU_DOWN_FAILED:
case CPU_ONLINE:
smp_call_function_single(cpu, nmi_cpu_start, NULL, 0);
smp_call_function_single(cpu, nmi_cpu_up, NULL, 0);
break;
case CPU_DOWN_PREPARE:
smp_call_function_single(cpu, nmi_cpu_stop, NULL, 1);
smp_call_function_single(cpu, nmi_cpu_down, NULL, 1);
break;
}
return NOTIFY_DONE;
@ -699,7 +731,11 @@ int __init op_nmi_init(struct oprofile_operations *ops)
return -ENODEV;
}
get_online_cpus();
register_cpu_notifier(&oprofile_cpu_nb);
nmi_enabled = 0;
ctr_running = 0;
put_online_cpus();
/* default values, can be overwritten by model */
ops->create_files = nmi_create_files;
@ -729,7 +765,11 @@ void op_nmi_exit(void)
{
if (using_nmi) {
exit_sysfs();
get_online_cpus();
unregister_cpu_notifier(&oprofile_cpu_nb);
nmi_enabled = 0;
ctr_running = 0;
put_online_cpus();
}
if (model->exit)
model->exit();