android_kernel_xiaomi_sm8350/arch/powerpc/platforms/pseries/hotplug-cpu.c
Sebastien Dugue b906cfa397 powerpc/pseries: Fix cpu hotplug
Currently, pseries_cpu_die() calls msleep() while polling RTAS for
the status of the dying cpu.

However, if the cpu that is going down also happens to be the one
doing the tick then we're hosed as the tick_do_timer_cpu 'baton' is
only passed later on in tick_shutdown() when _cpu_down() does the
CPU_DEAD notification.  Therefore jiffies won't be updated anymore.

This replaces that msleep() with a cpu_relax() to make sure we're not
going to schedule at that point.

With this patch my test box survives a 100k iterations hotplug stress
test on _all_ cpus, whereas without it, it quickly dies after ~50
iterations.

Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-12-23 15:13:27 +11:00

292 lines
7.3 KiB
C

/*
* pseries CPU Hotplug infrastructure.
*
* Split out from arch/powerpc/platforms/pseries/setup.c
* arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
*
* Peter Bergner, IBM March 2001.
* Copyright (C) 2001 IBM.
* Dave Engebretsen, Peter Bergner, and
* Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
* Plus various changes from other IBM teams...
*
* Copyright (C) 2006 Michael Ellerman, IBM Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <asm/system.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/vdso_datapage.h>
#include <asm/pSeries_reconfig.h>
#include "xics.h"
#include "plpar_wrappers.h"
/* This version can't take the spinlock, because it never returns */
static struct rtas_args rtas_stop_self_args = {
.token = RTAS_UNKNOWN_SERVICE,
.nargs = 0,
.nret = 1,
.rets = &rtas_stop_self_args.args[0],
};
static void rtas_stop_self(void)
{
struct rtas_args *args = &rtas_stop_self_args;
local_irq_disable();
BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
printk("cpu %u (hwid %u) Ready to die...\n",
smp_processor_id(), hard_smp_processor_id());
enter_rtas(__pa(args));
panic("Alas, I survived.\n");
}
static void pseries_mach_cpu_die(void)
{
local_irq_disable();
idle_task_exit();
xics_teardown_cpu();
unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
rtas_stop_self();
/* Should never get here... */
BUG();
for(;;);
}
static int qcss_tok; /* query-cpu-stopped-state token */
/* Get state of physical CPU.
* Return codes:
* 0 - The processor is in the RTAS stopped state
* 1 - stop-self is in progress
* 2 - The processor is not in the RTAS stopped state
* -1 - Hardware Error
* -2 - Hardware Busy, Try again later.
*/
static int query_cpu_stopped(unsigned int pcpu)
{
int cpu_status, status;
status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
if (status != 0) {
printk(KERN_ERR
"RTAS query-cpu-stopped-state failed: %i\n", status);
return status;
}
return cpu_status;
}
static int pseries_cpu_disable(void)
{
int cpu = smp_processor_id();
cpu_clear(cpu, cpu_online_map);
vdso_data->processorCount--;
/*fix boot_cpuid here*/
if (cpu == boot_cpuid)
boot_cpuid = any_online_cpu(cpu_online_map);
/* FIXME: abstract this to not be platform specific later on */
xics_migrate_irqs_away();
return 0;
}
static void pseries_cpu_die(unsigned int cpu)
{
int tries;
int cpu_status;
unsigned int pcpu = get_hard_smp_processor_id(cpu);
for (tries = 0; tries < 25; tries++) {
cpu_status = query_cpu_stopped(pcpu);
if (cpu_status == 0 || cpu_status == -1)
break;
cpu_relax();
}
if (cpu_status != 0) {
printk("Querying DEAD? cpu %i (%i) shows %i\n",
cpu, pcpu, cpu_status);
}
/* Isolation and deallocation are definatly done by
* drslot_chrp_cpu. If they were not they would be
* done here. Change isolate state to Isolate and
* change allocation-state to Unusable.
*/
paca[cpu].cpu_start = 0;
}
/*
* Update cpu_present_map and paca(s) for a new cpu node. The wrinkle
* here is that a cpu device node may represent up to two logical cpus
* in the SMT case. We must honor the assumption in other code that
* the logical ids for sibling SMT threads x and y are adjacent, such
* that x^1 == y and y^1 == x.
*/
static int pseries_add_processor(struct device_node *np)
{
unsigned int cpu;
cpumask_t candidate_map, tmp = CPU_MASK_NONE;
int err = -ENOSPC, len, nthreads, i;
const u32 *intserv;
intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
if (!intserv)
return 0;
nthreads = len / sizeof(u32);
for (i = 0; i < nthreads; i++)
cpu_set(i, tmp);
cpu_maps_update_begin();
BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
/* Get a bitmap of unoccupied slots. */
cpus_xor(candidate_map, cpu_possible_map, cpu_present_map);
if (cpus_empty(candidate_map)) {
/* If we get here, it most likely means that NR_CPUS is
* less than the partition's max processors setting.
*/
printk(KERN_ERR "Cannot add cpu %s; this system configuration"
" supports %d logical cpus.\n", np->full_name,
cpus_weight(cpu_possible_map));
goto out_unlock;
}
while (!cpus_empty(tmp))
if (cpus_subset(tmp, candidate_map))
/* Found a range where we can insert the new cpu(s) */
break;
else
cpus_shift_left(tmp, tmp, nthreads);
if (cpus_empty(tmp)) {
printk(KERN_ERR "Unable to find space in cpu_present_map for"
" processor %s with %d thread(s)\n", np->name,
nthreads);
goto out_unlock;
}
for_each_cpu_mask(cpu, tmp) {
BUG_ON(cpu_isset(cpu, cpu_present_map));
cpu_set(cpu, cpu_present_map);
set_hard_smp_processor_id(cpu, *intserv++);
}
err = 0;
out_unlock:
cpu_maps_update_done();
return err;
}
/*
* Update the present map for a cpu node which is going away, and set
* the hard id in the paca(s) to -1 to be consistent with boot time
* convention for non-present cpus.
*/
static void pseries_remove_processor(struct device_node *np)
{
unsigned int cpu;
int len, nthreads, i;
const u32 *intserv;
intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
if (!intserv)
return;
nthreads = len / sizeof(u32);
cpu_maps_update_begin();
for (i = 0; i < nthreads; i++) {
for_each_present_cpu(cpu) {
if (get_hard_smp_processor_id(cpu) != intserv[i])
continue;
BUG_ON(cpu_online(cpu));
cpu_clear(cpu, cpu_present_map);
set_hard_smp_processor_id(cpu, -1);
break;
}
if (cpu == NR_CPUS)
printk(KERN_WARNING "Could not find cpu to remove "
"with physical id 0x%x\n", intserv[i]);
}
cpu_maps_update_done();
}
static int pseries_smp_notifier(struct notifier_block *nb,
unsigned long action, void *node)
{
int err = NOTIFY_OK;
switch (action) {
case PSERIES_RECONFIG_ADD:
if (pseries_add_processor(node))
err = NOTIFY_BAD;
break;
case PSERIES_RECONFIG_REMOVE:
pseries_remove_processor(node);
break;
default:
err = NOTIFY_DONE;
break;
}
return err;
}
static struct notifier_block pseries_smp_nb = {
.notifier_call = pseries_smp_notifier,
};
static int __init pseries_cpu_hotplug_init(void)
{
struct device_node *np;
const char *typep;
for_each_node_by_name(np, "interrupt-controller") {
typep = of_get_property(np, "compatible", NULL);
if (strstr(typep, "open-pic")) {
of_node_put(np);
printk(KERN_INFO "CPU Hotplug not supported on "
"systems using MPIC\n");
return 0;
}
}
rtas_stop_self_args.token = rtas_token("stop-self");
qcss_tok = rtas_token("query-cpu-stopped-state");
if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
qcss_tok == RTAS_UNKNOWN_SERVICE) {
printk(KERN_INFO "CPU Hotplug not supported by firmware "
"- disabling.\n");
return 0;
}
ppc_md.cpu_die = pseries_mach_cpu_die;
smp_ops->cpu_disable = pseries_cpu_disable;
smp_ops->cpu_die = pseries_cpu_die;
/* Processors can be added/removed only on LPAR */
if (firmware_has_feature(FW_FEATURE_LPAR))
pSeries_reconfig_notifier_register(&pseries_smp_nb);
return 0;
}
arch_initcall(pseries_cpu_hotplug_init);