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SubjectRe: [PATCH 01/27] smpboot: Provide a generic method to boot secondary processors
On Fri, Jun 01, 2012 at 05:39:27PM +0530, Srivatsa S. Bhat wrote:
> +/* Implement the following functions in your architecture, as appropriate. */
> +
> +/**
> + * __cpu_pre_starting()
> + *
> + * Implement whatever you need to do before the CPU_STARTING notifiers are
> + * invoked. Note that the CPU_STARTING callbacks run *on* the cpu that is
> + * coming up. So that cpu better be prepared! IOW, implement all the early
> + * boot/init code for the cpu here. And do NOT enable interrupts.
> + */
> +#ifndef __cpu_pre_starting

Why the ifndef?

Thanks,
Yong

> +void __weak __cpu_pre_starting(void *arg) {}
> +#endif
> +
> +/**
> + * __cpu_pre_online()
> + *
> + * Implement whatever you need to do before the upcoming CPU is set in the
> + * cpu_online_mask. (Setting the cpu in the cpu_online_mask is like an
> + * announcement that the cpu has come up, because it would be publicly
> + * visible now). Again, don't enable interrupts.
> + */
> +#ifndef __cpu_pre_online
> +void __weak __cpu_pre_online(void *arg) {}
> +#endif
> +
> +/**
> + * __cpu_post_online()
> + *
> + * Implement whatever you need to do after the CPU has been set in the
> + * cpu_online_mask, and before enabling interrupts and calling cpu_idle().
> + * Ideally, it is preferable if you don't have anything to do here.
> + * We want to move to a model where setting cpu_online_mask is pretty
> + * much the final step. Again, don't enable interrupts.
> + */
> +#ifndef __cpu_post_online
> +void __weak __cpu_post_online(void *arg) {}
> +#endif
> +
> +
> +/**
> + * smpboot_start_secondary - Generic way to boot secondary processors
> + */
> +void __cpuinit smpboot_start_secondary(void *arg)
> +{
> + unsigned int cpu;
> +
> + /*
> + * SMP booting is extremely fragile in some architectures. So run
> + * the cpu initialization code first before anything else.
> + */
> + __cpu_pre_starting(arg);
> +
> + preempt_disable();
> + cpu = smp_processor_id();
> +
> + /* Invoke the CPU_STARTING notifier callbacks */
> + notify_cpu_starting(cpu);
> +
> + __cpu_pre_online(arg);
> +
> + /* Set the CPU in the cpu_online_mask */
> + set_cpu_online(cpu, true);
> +
> + __cpu_post_online(arg);
> +
> + /* Enable local interrupts now */
> + local_irq_enable();
> +
> + wmb();
> + cpu_idle();
> +
> + /* We should never reach here! */
> + BUG();
> +}
> diff --git a/kernel/smpboot.h b/kernel/smpboot.h
> index 80c0acf..9753cc0 100644
> --- a/kernel/smpboot.h
> +++ b/kernel/smpboot.h
> @@ -1,5 +1,5 @@
> -#ifndef SMPBOOT_H
> -#define SMPBOOT_H
> +#ifndef __SMPBOOT_H
> +#define __SMPBOOT_H
>
> struct task_struct;
>
>
>
> From: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Subject: [PATCH 02/27] smpboot: Add provisions for arch-specific locking around cpu_online_mask
>
> We want to make smp booting as generic as possible and remove code
> duplication in arch/ directories.
>
> While manipulating the cpu_online_mask, x86 uses an additional lock, i.e.,
> 'vector_lock'. So provide a generic way to implement such arch-specific
> extra locking, by providing weakly defined functions arch_vector_lock()
> and arch_vector_unlock() which can be overriden by different architectures
> suitably.
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Suresh Siddha <suresh.b.siddha@intel.com>
> Cc: Venkatesh Pallipadi <venki@google.com>
> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> ---
>
> kernel/smpboot.c | 11 ++++++++++-
> 1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/smpboot.c b/kernel/smpboot.c
> index 6c26133..5ae1805 100644
> --- a/kernel/smpboot.c
> +++ b/kernel/smpboot.c
> @@ -107,6 +107,13 @@ void __weak __cpu_pre_online(void *arg) {}
> void __weak __cpu_post_online(void *arg) {}
> #endif
>
> +/*
> + * Optional arch-specific locking for manipulating cpu_online_mask while
> + * bringing up secondary CPUs.
> + */
> +void __weak arch_vector_lock(void) {}
> +void __weak arch_vector_unlock(void) {}
> +
>
> /**
> * smpboot_start_secondary - Generic way to boot secondary processors
> @@ -129,8 +136,10 @@ void __cpuinit smpboot_start_secondary(void *arg)
>
> __cpu_pre_online(arg);
>
> - /* Set the CPU in the cpu_online_mask */
> + /* Set the CPU in the cpu_online_mask with required locks held */
> + arch_vector_lock();
> set_cpu_online(cpu, true);
> + arch_vector_unlock();
>
> __cpu_post_online(arg);
>
>
>
> From: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Subject: [PATCH 03/27] smpboot: Define and use cpu_state per-cpu variable in generic code
>
> The per-cpu variable cpu_state is used in x86 and also used in other
> architectures, to track the state of the cpu during bringup and hotplug.
> Pull it out into generic code.
>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mundt <lethal@linux-sh.org>
> Cc: Chris Metcalf <cmetcalf@tilera.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Mike Frysinger <vapier@gentoo.org>
> Cc: Yong Zhang <yong.zhang0@gmail.com>
> Cc: Venkatesh Pallipadi <venki@google.com>
> Cc: Suresh Siddha <suresh.b.siddha@intel.com>
> Cc: linux-ia64@vger.kernel.org
> Cc: linux-mips@linux-mips.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-sh@vger.kernel.org
> Cc: xen-devel@lists.xensource.com
> Cc: virtualization@lists.linux-foundation.org
> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> ---
>
> arch/ia64/include/asm/cpu.h | 2 --
> arch/ia64/kernel/process.c | 1 +
> arch/ia64/kernel/smpboot.c | 6 +-----
> arch/mips/cavium-octeon/smp.c | 4 +---
> arch/powerpc/kernel/smp.c | 6 +-----
> arch/sh/include/asm/smp.h | 2 --
> arch/sh/kernel/smp.c | 4 +---
> arch/tile/kernel/smpboot.c | 4 +---
> arch/x86/include/asm/cpu.h | 2 --
> arch/x86/kernel/smpboot.c | 4 +---
> arch/x86/xen/smp.c | 1 +
> include/linux/smpboot.h | 1 +
> kernel/smpboot.c | 4 ++++
> 13 files changed, 13 insertions(+), 28 deletions(-)
>
> diff --git a/arch/ia64/include/asm/cpu.h b/arch/ia64/include/asm/cpu.h
> index fcca30b..1c3acac 100644
> --- a/arch/ia64/include/asm/cpu.h
> +++ b/arch/ia64/include/asm/cpu.h
> @@ -12,8 +12,6 @@ struct ia64_cpu {
>
> DECLARE_PER_CPU(struct ia64_cpu, cpu_devices);
>
> -DECLARE_PER_CPU(int, cpu_state);
> -
> #ifdef CONFIG_HOTPLUG_CPU
> extern int arch_register_cpu(int num);
> extern void arch_unregister_cpu(int);
> diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
> index 5e0e86d..32566c7 100644
> --- a/arch/ia64/kernel/process.c
> +++ b/arch/ia64/kernel/process.c
> @@ -29,6 +29,7 @@
> #include <linux/kdebug.h>
> #include <linux/utsname.h>
> #include <linux/tracehook.h>
> +#include <linux/smpboot.h>
>
> #include <asm/cpu.h>
> #include <asm/delay.h>
> diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
> index 963d2db..df00a3c 100644
> --- a/arch/ia64/kernel/smpboot.c
> +++ b/arch/ia64/kernel/smpboot.c
> @@ -39,6 +39,7 @@
> #include <linux/efi.h>
> #include <linux/percpu.h>
> #include <linux/bitops.h>
> +#include <linux/smpboot.h>
>
> #include <linux/atomic.h>
> #include <asm/cache.h>
> @@ -111,11 +112,6 @@ extern unsigned long ia64_iobase;
>
> struct task_struct *task_for_booting_cpu;
>
> -/*
> - * State for each CPU
> - */
> -DEFINE_PER_CPU(int, cpu_state);
> -
> cpumask_t cpu_core_map[NR_CPUS] __cacheline_aligned;
> EXPORT_SYMBOL(cpu_core_map);
> DEFINE_PER_CPU_SHARED_ALIGNED(cpumask_t, cpu_sibling_map);
> diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
> index 97e7ce9..93cd4b0 100644
> --- a/arch/mips/cavium-octeon/smp.c
> +++ b/arch/mips/cavium-octeon/smp.c
> @@ -13,6 +13,7 @@
> #include <linux/kernel_stat.h>
> #include <linux/sched.h>
> #include <linux/module.h>
> +#include <linux/smpboot.h>
>
> #include <asm/mmu_context.h>
> #include <asm/time.h>
> @@ -252,9 +253,6 @@ static void octeon_cpus_done(void)
>
> #ifdef CONFIG_HOTPLUG_CPU
>
> -/* State of each CPU. */
> -DEFINE_PER_CPU(int, cpu_state);
> -
> extern void fixup_irqs(void);
>
> static DEFINE_SPINLOCK(smp_reserve_lock);
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index e1417c4..1928058a 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -31,6 +31,7 @@
> #include <linux/cpu.h>
> #include <linux/notifier.h>
> #include <linux/topology.h>
> +#include <linux/smpboot.h>
>
> #include <asm/ptrace.h>
> #include <linux/atomic.h>
> @@ -57,11 +58,6 @@
> #define DBG(fmt...)
> #endif
>
> -#ifdef CONFIG_HOTPLUG_CPU
> -/* State of each CPU during hotplug phases */
> -static DEFINE_PER_CPU(int, cpu_state) = { 0 };
> -#endif
> -
> struct thread_info *secondary_ti;
>
> DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
> diff --git a/arch/sh/include/asm/smp.h b/arch/sh/include/asm/smp.h
> index 78b0d0f4..bda041e 100644
> --- a/arch/sh/include/asm/smp.h
> +++ b/arch/sh/include/asm/smp.h
> @@ -31,8 +31,6 @@ enum {
> SMP_MSG_NR, /* must be last */
> };
>
> -DECLARE_PER_CPU(int, cpu_state);
> -
> void smp_message_recv(unsigned int msg);
> void smp_timer_broadcast(const struct cpumask *mask);
>
> diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
> index b86e9ca..8e0fde0 100644
> --- a/arch/sh/kernel/smp.c
> +++ b/arch/sh/kernel/smp.c
> @@ -22,6 +22,7 @@
> #include <linux/interrupt.h>
> #include <linux/sched.h>
> #include <linux/atomic.h>
> +#include <linux/smpboot.h>
> #include <asm/processor.h>
> #include <asm/mmu_context.h>
> #include <asm/smp.h>
> @@ -34,9 +35,6 @@ int __cpu_logical_map[NR_CPUS]; /* Map logical to physical */
>
> struct plat_smp_ops *mp_ops = NULL;
>
> -/* State of each CPU */
> -DEFINE_PER_CPU(int, cpu_state) = { 0 };
> -
> void __cpuinit register_smp_ops(struct plat_smp_ops *ops)
> {
> if (mp_ops)
> diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c
> index e686c5a..24a9c06 100644
> --- a/arch/tile/kernel/smpboot.c
> +++ b/arch/tile/kernel/smpboot.c
> @@ -25,13 +25,11 @@
> #include <linux/delay.h>
> #include <linux/err.h>
> #include <linux/irq.h>
> +#include <linux/smpboot.h>
> #include <asm/mmu_context.h>
> #include <asm/tlbflush.h>
> #include <asm/sections.h>
>
> -/* State of each CPU. */
> -static DEFINE_PER_CPU(int, cpu_state) = { 0 };
> -
> /* The messaging code jumps to this pointer during boot-up */
> unsigned long start_cpu_function_addr;
>
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index 4564c8e..2d0b239 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -30,8 +30,6 @@ extern int arch_register_cpu(int num);
> extern void arch_unregister_cpu(int);
> #endif
>
> -DECLARE_PER_CPU(int, cpu_state);
> -
> int mwait_usable(const struct cpuinfo_x86 *);
>
> #endif /* _ASM_X86_CPU_H */
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index bfbe30e..269bc1f 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -51,6 +51,7 @@
> #include <linux/stackprotector.h>
> #include <linux/gfp.h>
> #include <linux/cpuidle.h>
> +#include <linux/smpboot.h>
>
> #include <asm/acpi.h>
> #include <asm/desc.h>
> @@ -73,9 +74,6 @@
> #include <asm/smpboot_hooks.h>
> #include <asm/i8259.h>
>
> -/* State of each CPU */
> -DEFINE_PER_CPU(int, cpu_state) = { 0 };
> -
> #ifdef CONFIG_HOTPLUG_CPU
> /*
> * We need this for trampoline_base protection from concurrent accesses when
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index 2ef5948..09a7199 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -16,6 +16,7 @@
> #include <linux/err.h>
> #include <linux/slab.h>
> #include <linux/smp.h>
> +#include <linux/smpboot.h>
>
> #include <asm/paravirt.h>
> #include <asm/desc.h>
> diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
> index 63bbedd..834d90c 100644
> --- a/include/linux/smpboot.h
> +++ b/include/linux/smpboot.h
> @@ -5,6 +5,7 @@
> #ifndef SMPBOOT_H
> #define SMPBOOT_H
>
> +DECLARE_PER_CPU(int, cpu_state);
> extern void smpboot_start_secondary(void *arg);
>
> #endif
> diff --git a/kernel/smpboot.c b/kernel/smpboot.c
> index 5ae1805..0df43b0 100644
> --- a/kernel/smpboot.c
> +++ b/kernel/smpboot.c
> @@ -67,6 +67,8 @@ void __init idle_threads_init(void)
> }
> #endif
>
> +/* State of each CPU during bringup/teardown */
> +DEFINE_PER_CPU(int, cpu_state) = { 0 };
>
> /* Implement the following functions in your architecture, as appropriate. */
>
> @@ -141,6 +143,8 @@ void __cpuinit smpboot_start_secondary(void *arg)
> set_cpu_online(cpu, true);
> arch_vector_unlock();
>
> + per_cpu(cpu_state, cpu) = CPU_ONLINE;
> +
> __cpu_post_online(arg);
>
> /* Enable local interrupts now */
>
>
> --
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