[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 <ak@suse.de>

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 4f67697f5036faf1f37222ced236c0b3a04626c7..9f74c883568c419909b6542449161d5b109f6b51 100644 (file)
--- 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 88722f11ca132595cf11704e8e65cdb47e2790f9..e3ef544d2cfb514f1894c232c0e8d38e456a49f7 100644 (file)
--- 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 a98b460af6a1f600ebc2153490ecd4706700d08e..a730bacecb0be186625cb0cec338f76e1dc6b6c0 100644 (file)
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -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;
 }
 

diff --git a/include/asm-x86_64/vsyscall.h b/include/asm-x86_64/vsyscall.h
index fd452fc2c037d7b08765905161ede0df52ccdef9..01d1c17e2849abb50a2bf4bffb4185a726d886f5 100644 (file)
--- 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__ */