[PATCH] Check if cpu can be onlined before calling smp_prepare_cpu()

- Moved check for online cpu out of smp_prepare_cpu()

- Moved default declaration of smp_prepare_cpu() to kernel/cpu.c

- Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
  its called from cpu_up() as well now.

- Removed clearing from cpu_present_map during cpu_offline as it breaks
  using cpu_up() directly during a subsequent online operation.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 4c470e9..82371d8 100644 (file)
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -1003,7 +1003,6 @@ void cpu_exit_clear(void)
 
        cpu_clear(cpu, cpu_callout_map);
        cpu_clear(cpu, cpu_callin_map);
-       cpu_clear(cpu, cpu_present_map);
 
        cpu_clear(cpu, smp_commenced_mask);
        unmap_cpu_to_logical_apicid(cpu);
@@ -1015,31 +1014,20 @@ struct warm_boot_cpu_info {
        int cpu;
 };
 
-static void __devinit do_warm_boot_cpu(void *p)
+static void __cpuinit do_warm_boot_cpu(void *p)
 {
        struct warm_boot_cpu_info *info = p;
        do_boot_cpu(info->apicid, info->cpu);
        complete(info->complete);
 }
 
-int __devinit smp_prepare_cpu(int cpu)
+static int __cpuinit __smp_prepare_cpu(int cpu)
 {
        DECLARE_COMPLETION(done);
        struct warm_boot_cpu_info info;
        struct work_struct task;
        int     apicid, ret;
 
-       lock_cpu_hotplug();
-
-       /*
-        * On x86, CPU0 is never offlined.  Trying to bring up an
-        * already-booted CPU will hang.  So check for that case.
-        */
-       if (cpu_online(cpu)) {
-               ret = -EINVAL;
-               goto exit;
-       }
-
        apicid = x86_cpu_to_apicid[cpu];
        if (apicid == BAD_APICID) {
                ret = -ENODEV;
@@ -1064,7 +1052,6 @@ int __devinit smp_prepare_cpu(int cpu)
        zap_low_mappings();
        ret = 0;
 exit:
-       unlock_cpu_hotplug();
        return ret;
 }
 #endif
@@ -1392,6 +1379,22 @@ void __cpu_die(unsigned int cpu)
 
 int __devinit __cpu_up(unsigned int cpu)
 {
+#ifdef CONFIG_HOTPLUG_CPU
+       int ret=0;
+
+       /*
+        * We do warm boot only on cpus that had booted earlier
+        * Otherwise cold boot is all handled from smp_boot_cpus().
+        * cpu_callin_map is set during AP kickstart process. Its reset
+        * when a cpu is taken offline from cpu_exit_clear().
+        */
+       if (!cpu_isset(cpu, cpu_callin_map))
+               ret = __smp_prepare_cpu(cpu);
+
+       if (ret)
+               return -EIO;
+#endif
+
        /* In case one didn't come up */
        if (!cpu_isset(cpu, cpu_callin_map)) {
                printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu);

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 29f3d75..dd712b2 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -19,11 +19,6 @@ EXPORT_SYMBOL(cpu_sysdev_class);
 static struct sys_device *cpu_sys_devices[NR_CPUS];
 
 #ifdef CONFIG_HOTPLUG_CPU
-int __attribute__((weak)) smp_prepare_cpu (int cpu)
-{
-       return 0;
-}
-
 static ssize_t show_online(struct sys_device *dev, char *buf)
 {
        struct cpu *cpu = container_of(dev, struct cpu, sysdev);
@@ -44,9 +39,7 @@ static ssize_t store_online(struct sys_device *dev, const char *buf,
                        kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
                break;
        case '1':
-               ret = smp_prepare_cpu(cpu->sysdev.id);
-               if (!ret)
-                       ret = cpu_up(cpu->sysdev.id);
+               ret = cpu_up(cpu->sysdev.id);
                if (!ret)
                        kobject_uevent(&dev->kobj, KOBJ_ONLINE);
                break;

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d612b89..08d50c5 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -74,7 +74,6 @@ extern int lock_cpu_hotplug_interruptible(void);
        register_cpu_notifier(&fn##_nb);                        \
 }
 int cpu_down(unsigned int cpu);
-extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
 #else
 #define lock_cpu_hotplug()     do { } while (0)

diff --git a/kernel/power/smp.c b/kernel/power/smp.c
index 911fc62..5957312 100644 (file)
--- a/kernel/power/smp.c
+++ b/kernel/power/smp.c
@@ -49,9 +49,7 @@ void enable_nonboot_cpus(void)
 
        printk("Thawing cpus ...\n");
        for_each_cpu_mask(cpu, frozen_cpus) {
-               error = smp_prepare_cpu(cpu);
-               if (!error)
-                       error = cpu_up(cpu);
+               error = cpu_up(cpu);
                if (!error) {
                        printk("CPU%d is up\n", cpu);
                        continue;