From 8c131af1db510793f87dc43edbc8950a35370df3 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Tue, 14 Nov 2006 16:57:46 +0100 Subject: [PATCH] [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: Andi Kleen --- arch/x86_64/kernel/smp.c | 3 +-- arch/x86_64/kernel/time.c | 11 --------- arch/x86_64/kernel/vsyscall.c | 45 +++++++++++++++++++---------------- include/asm-x86_64/vsyscall.h | 2 -- 4 files changed, 26 insertions(+), 35 deletions(-) diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c index 4f67697f50..9f74c88356 100644 --- a/arch/x86_64/kernel/smp.c +++ b/arch/x86_64/kernel/smp.c @@ -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); diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 88722f11ca..e3ef544d2c 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -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(); diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c index a98b460af6..a730bacecb 100644 --- a/arch/x86_64/kernel/vsyscall.c +++ b/arch/x86_64/kernel/vsyscall.c @@ -27,6 +27,9 @@ #include #include #include +#include +#include +#include #include #include @@ -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; } diff --git a/include/asm-x86_64/vsyscall.h b/include/asm-x86_64/vsyscall.h index fd452fc2c0..01d1c17e28 100644 --- a/include/asm-x86_64/vsyscall.h +++ b/include/asm-x86_64/vsyscall.h @@ -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__ */ -- 2.39.5