86ef5c9a8e
Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use get_online_cpus and put_online_cpus instead as it highlights the refcount semantics in these operations. The new API guarantees protection against the cpu-hotplug operation, but it doesn't guarantee serialized access to any of the local data structures. Hence the changes needs to be reviewed. In case of pseries_add_processor/pseries_remove_processor, use cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the cpu_present_map there. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
292 lines
7.3 KiB
C
292 lines
7.3 KiB
C
/*
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* pseries CPU Hotplug infrastructure.
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*
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* Split out from arch/powerpc/platforms/pseries/setup.c
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* arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
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*
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* Peter Bergner, IBM March 2001.
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* Copyright (C) 2001 IBM.
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* Dave Engebretsen, Peter Bergner, and
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* Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
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* Plus various changes from other IBM teams...
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*
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* Copyright (C) 2006 Michael Ellerman, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/cpu.h>
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#include <asm/system.h>
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#include <asm/prom.h>
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#include <asm/rtas.h>
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#include <asm/firmware.h>
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#include <asm/machdep.h>
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#include <asm/vdso_datapage.h>
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#include <asm/pSeries_reconfig.h>
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#include "xics.h"
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#include "plpar_wrappers.h"
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/* This version can't take the spinlock, because it never returns */
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static struct rtas_args rtas_stop_self_args = {
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.token = RTAS_UNKNOWN_SERVICE,
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.nargs = 0,
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.nret = 1,
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.rets = &rtas_stop_self_args.args[0],
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};
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static void rtas_stop_self(void)
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{
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struct rtas_args *args = &rtas_stop_self_args;
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local_irq_disable();
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BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
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printk("cpu %u (hwid %u) Ready to die...\n",
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smp_processor_id(), hard_smp_processor_id());
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enter_rtas(__pa(args));
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panic("Alas, I survived.\n");
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}
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static void pseries_mach_cpu_die(void)
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{
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local_irq_disable();
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idle_task_exit();
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xics_teardown_cpu(0);
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unregister_slb_shadow(hard_smp_processor_id(), __pa(get_slb_shadow()));
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rtas_stop_self();
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/* Should never get here... */
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BUG();
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for(;;);
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}
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static int qcss_tok; /* query-cpu-stopped-state token */
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/* Get state of physical CPU.
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* Return codes:
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* 0 - The processor is in the RTAS stopped state
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* 1 - stop-self is in progress
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* 2 - The processor is not in the RTAS stopped state
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* -1 - Hardware Error
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* -2 - Hardware Busy, Try again later.
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*/
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static int query_cpu_stopped(unsigned int pcpu)
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{
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int cpu_status, status;
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status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
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if (status != 0) {
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printk(KERN_ERR
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"RTAS query-cpu-stopped-state failed: %i\n", status);
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return status;
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}
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return cpu_status;
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}
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static int pseries_cpu_disable(void)
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{
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int cpu = smp_processor_id();
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cpu_clear(cpu, cpu_online_map);
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vdso_data->processorCount--;
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/*fix boot_cpuid here*/
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if (cpu == boot_cpuid)
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boot_cpuid = any_online_cpu(cpu_online_map);
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/* FIXME: abstract this to not be platform specific later on */
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xics_migrate_irqs_away();
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return 0;
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}
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static void pseries_cpu_die(unsigned int cpu)
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{
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int tries;
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int cpu_status;
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unsigned int pcpu = get_hard_smp_processor_id(cpu);
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for (tries = 0; tries < 25; tries++) {
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cpu_status = query_cpu_stopped(pcpu);
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if (cpu_status == 0 || cpu_status == -1)
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break;
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msleep(200);
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}
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if (cpu_status != 0) {
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printk("Querying DEAD? cpu %i (%i) shows %i\n",
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cpu, pcpu, cpu_status);
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}
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/* Isolation and deallocation are definatly done by
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* drslot_chrp_cpu. If they were not they would be
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* done here. Change isolate state to Isolate and
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* change allocation-state to Unusable.
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*/
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paca[cpu].cpu_start = 0;
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}
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/*
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* Update cpu_present_map and paca(s) for a new cpu node. The wrinkle
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* here is that a cpu device node may represent up to two logical cpus
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* in the SMT case. We must honor the assumption in other code that
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* the logical ids for sibling SMT threads x and y are adjacent, such
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* that x^1 == y and y^1 == x.
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*/
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static int pseries_add_processor(struct device_node *np)
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{
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unsigned int cpu;
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cpumask_t candidate_map, tmp = CPU_MASK_NONE;
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int err = -ENOSPC, len, nthreads, i;
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const u32 *intserv;
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intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
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if (!intserv)
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return 0;
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nthreads = len / sizeof(u32);
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for (i = 0; i < nthreads; i++)
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cpu_set(i, tmp);
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cpu_maps_update_begin();
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BUG_ON(!cpus_subset(cpu_present_map, cpu_possible_map));
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/* Get a bitmap of unoccupied slots. */
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cpus_xor(candidate_map, cpu_possible_map, cpu_present_map);
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if (cpus_empty(candidate_map)) {
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/* If we get here, it most likely means that NR_CPUS is
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* less than the partition's max processors setting.
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*/
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printk(KERN_ERR "Cannot add cpu %s; this system configuration"
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" supports %d logical cpus.\n", np->full_name,
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cpus_weight(cpu_possible_map));
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goto out_unlock;
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}
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while (!cpus_empty(tmp))
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if (cpus_subset(tmp, candidate_map))
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/* Found a range where we can insert the new cpu(s) */
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break;
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else
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cpus_shift_left(tmp, tmp, nthreads);
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if (cpus_empty(tmp)) {
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printk(KERN_ERR "Unable to find space in cpu_present_map for"
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" processor %s with %d thread(s)\n", np->name,
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nthreads);
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goto out_unlock;
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}
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for_each_cpu_mask(cpu, tmp) {
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BUG_ON(cpu_isset(cpu, cpu_present_map));
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cpu_set(cpu, cpu_present_map);
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set_hard_smp_processor_id(cpu, *intserv++);
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}
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err = 0;
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out_unlock:
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cpu_maps_update_done();
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return err;
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}
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/*
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* Update the present map for a cpu node which is going away, and set
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* the hard id in the paca(s) to -1 to be consistent with boot time
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* convention for non-present cpus.
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*/
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static void pseries_remove_processor(struct device_node *np)
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{
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unsigned int cpu;
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int len, nthreads, i;
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const u32 *intserv;
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intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
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if (!intserv)
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return;
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nthreads = len / sizeof(u32);
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cpu_maps_update_begin();
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for (i = 0; i < nthreads; i++) {
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for_each_present_cpu(cpu) {
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if (get_hard_smp_processor_id(cpu) != intserv[i])
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continue;
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BUG_ON(cpu_online(cpu));
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cpu_clear(cpu, cpu_present_map);
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set_hard_smp_processor_id(cpu, -1);
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break;
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}
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if (cpu == NR_CPUS)
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printk(KERN_WARNING "Could not find cpu to remove "
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"with physical id 0x%x\n", intserv[i]);
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}
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cpu_maps_update_done();
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}
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static int pseries_smp_notifier(struct notifier_block *nb,
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unsigned long action, void *node)
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{
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int err = NOTIFY_OK;
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switch (action) {
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case PSERIES_RECONFIG_ADD:
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if (pseries_add_processor(node))
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err = NOTIFY_BAD;
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break;
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case PSERIES_RECONFIG_REMOVE:
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pseries_remove_processor(node);
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break;
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default:
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err = NOTIFY_DONE;
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break;
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}
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return err;
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}
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static struct notifier_block pseries_smp_nb = {
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.notifier_call = pseries_smp_notifier,
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};
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static int __init pseries_cpu_hotplug_init(void)
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{
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struct device_node *np;
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const char *typep;
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for_each_node_by_name(np, "interrupt-controller") {
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typep = of_get_property(np, "compatible", NULL);
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if (strstr(typep, "open-pic")) {
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of_node_put(np);
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printk(KERN_INFO "CPU Hotplug not supported on "
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"systems using MPIC\n");
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return 0;
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}
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}
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rtas_stop_self_args.token = rtas_token("stop-self");
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qcss_tok = rtas_token("query-cpu-stopped-state");
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if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
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qcss_tok == RTAS_UNKNOWN_SERVICE) {
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printk(KERN_INFO "CPU Hotplug not supported by firmware "
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"- disabling.\n");
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return 0;
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}
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ppc_md.cpu_die = pseries_mach_cpu_die;
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smp_ops->cpu_disable = pseries_cpu_disable;
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smp_ops->cpu_die = pseries_cpu_die;
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/* Processors can be added/removed only on LPAR */
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if (firmware_has_feature(FW_FEATURE_LPAR))
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pSeries_reconfig_notifier_register(&pseries_smp_nb);
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return 0;
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}
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arch_initcall(pseries_cpu_hotplug_init);
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