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Commit 8c131af1 authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen
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[PATCH] x86-64: Fix vgetcpu when CONFIG_HOTPLUG_CPU is disabled 



The vgetcpu per CPU initialization previously relied on CPU hotplug
events for all CPUs to initialize the per CPU state. That only
worked only on kernels with CONFIG_HOTPLUG_CPU enabled.  On the
others some CPUs didn't get their state initialized properly
and vgetcpu wouldn't work.

Change the initialization sequence to instead run in a normal
initcall (which runs after the normal CPU bootup) and initialize
all running CPUs there. Later hotplug CPUs are still handled
with an hotplug notifier.

This actually simplifies the code somewhat.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent fa18f477

arch/x86_64/kernel/smp.c

+1 −2
Original line number Diff line number Diff line
@@ -376,9 +376,8 @@ int smp_call_function_single (int cpu, void (*func) (void *info), void *info, 
	/* prevent preemption and reschedule on another processor */

	int me = get_cpu();

	if (cpu == me) {

		WARN_ON(1);

		put_cpu();

		return -EBUSY;

		return 0;

	}

	spin_lock_bh(&call_lock);

	__smp_call_function_single(cpu, func, info, nonatomic, wait);

arch/x86_64/kernel/time.c

+0 −11
Original line number Diff line number Diff line
@@ -876,15 +876,6 @@ static struct irqaction irq0 = { 
	timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL

};



static int __cpuinit

time_cpu_notifier(struct notifier_block *nb, unsigned long action, void *hcpu)

{

	unsigned cpu = (unsigned long) hcpu;

	if (action == CPU_ONLINE)

		vsyscall_set_cpu(cpu);

	return NOTIFY_DONE;

}



void __init time_init(void)

{

	if (nohpet)
@@ -925,8 +916,6 @@ void __init time_init(void) 
	vxtime.last_tsc = get_cycles_sync();

	set_cyc2ns_scale(cpu_khz);

	setup_irq(0, &irq0);

	hotcpu_notifier(time_cpu_notifier, 0);

	time_cpu_notifier(NULL, CPU_ONLINE, (void *)(long)smp_processor_id());



#ifndef CONFIG_SMP

	time_init_gtod();

arch/x86_64/kernel/vsyscall.c

+25 −20
Original line number Diff line number Diff line
@@ -27,6 +27,9 @@ 
#include <linux/jiffies.h>

#include <linux/sysctl.h>

#include <linux/getcpu.h>

#include <linux/cpu.h>

#include <linux/smp.h>

#include <linux/notifier.h>



#include <asm/vsyscall.h>

#include <asm/pgtable.h>
@@ -243,32 +246,17 @@ static ctl_table kernel_root_table2[] = { 


#endif



static void __cpuinit write_rdtscp_cb(void *info)

{

	write_rdtscp_aux((unsigned long)info);

}



void __cpuinit vsyscall_set_cpu(int cpu)

/* Assume __initcall executes before all user space. Hopefully kmod

   doesn't violate that. We'll find out if it does. */

static void __cpuinit vsyscall_set_cpu(int cpu)

{

	unsigned long *d;

	unsigned long node = 0;

#ifdef CONFIG_NUMA

	node = cpu_to_node[cpu];

#endif

	if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP)) {

		void *info = (void *)((node << 12) | cpu);

		/* Can happen on preemptive kernel */

		if (get_cpu() == cpu)

			write_rdtscp_cb(info);

#ifdef CONFIG_SMP

		else {

			/* the notifier is unfortunately not executed on the

			   target CPU */

			smp_call_function_single(cpu,write_rdtscp_cb,info,0,1);

		}

#endif

		put_cpu();

	}

	if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP))

		write_rdtscp_aux((node << 12) | cpu);



	/* Store cpu number in limit so that it can be loaded quickly

	   in user space in vgetcpu.
@@ -280,6 +268,21 @@ void __cpuinit vsyscall_set_cpu(int cpu) 
	*d |= (node >> 4) << 48;

}



static void __cpuinit cpu_vsyscall_init(void *arg)

{

	/* preemption should be already off */

	vsyscall_set_cpu(raw_smp_processor_id());

}



static int __cpuinit

cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)

{

	long cpu = (long)arg;

	if (action == CPU_ONLINE)

		smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 0, 1);

	return NOTIFY_DONE;

}



static void __init map_vsyscall(void)

{

	extern char __vsyscall_0;
@@ -299,6 +302,8 @@ static int __init vsyscall_init(void) 
#ifdef CONFIG_SYSCTL

	register_sysctl_table(kernel_root_table2, 0);

#endif

	on_each_cpu(cpu_vsyscall_init, NULL, 0, 1);

	hotcpu_notifier(cpu_vsyscall_notifier, 0);

	return 0;

}

include/asm-x86_64/vsyscall.h

+0 −2
Original line number Diff line number Diff line
@@ -59,8 +59,6 @@ extern seqlock_t xtime_lock; 


extern int sysctl_vsyscall;



extern void vsyscall_set_cpu(int cpu);



#define ARCH_HAVE_XTIME_LOCK 1



#endif /* __KERNEL__ */