1 files changed, 50 insertions, 31 deletions

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 5318f0cbfc26..ca1536db3394 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -9,6 +9,7 @@
  * 02/07/31 David Mosberger <davidm@hpl.hp.com> Switch over to hotplug-CPU boot-sequence.
  *                                              smp_boot_cpus()/smp_commence() is replaced by
  *                                              smp_prepare_cpus()/__cpu_up()/smp_cpus_done().
+ * 04/06/21 Ashok Raj           <ashok.raj@intel.com> Added CPU Hotplug Support
  */
 #include <linux/config.h>
 
@@ -58,6 +59,37 @@
 #define Dprintk(x...)
 #endif
 
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Store all idle threads, this can be reused instead of creating
+ * a new thread. Also avoids complicated thread destroy functionality
+ * for idle threads.
+ */
+struct task_struct *idle_thread_array[NR_CPUS];
+
+/*
+ * Global array allocated for NR_CPUS at boot time
+ */
+struct sal_to_os_boot sal_boot_rendez_state[NR_CPUS];
+
+/*
+ * start_ap in head.S uses this to store current booting cpu
+ * info.
+ */
+struct sal_to_os_boot *sal_state_for_booting_cpu = &sal_boot_rendez_state[0];
+
+#define set_brendez_area(x) (sal_state_for_booting_cpu = &sal_boot_rendez_state[(x)]);
+
+#define get_idle_for_cpu(x)             (idle_thread_array[(x)])
+#define set_idle_for_cpu(x,p)   (idle_thread_array[(x)] = (p))
+
+#else
+
+#define get_idle_for_cpu(x)             (NULL)
+#define set_idle_for_cpu(x,p)
+#define set_brendez_area(x)
+#endif
+
 
 /*
  * ITC synchronization related stuff:
@@ -345,7 +377,6 @@ start_secondary (void *unused)
 {
         /* Early console may use I/O ports */
         ia64_set_kr(IA64_KR_IO_BASE, __pa(ia64_iobase));
-
         Dprintk("start_secondary: starting CPU 0x%x\n", hard_smp_processor_id());
         efi_map_pal_code();
         cpu_init();
@@ -384,6 +415,13 @@ do_boot_cpu (int sapicid, int cpu)
                 .done   = COMPLETION_INITIALIZER(c_idle.done),
         };
         DECLARE_WORK(work, do_fork_idle, &c_idle);
+
+        c_idle.idle = get_idle_for_cpu(cpu);
+        if (c_idle.idle) {
+                init_idle(c_idle.idle, cpu);
+                goto do_rest;
+        }
+
         /*
          * We can't use kernel_thread since we must avoid to reschedule the child.
          */
@@ -396,10 +434,15 @@ do_boot_cpu (int sapicid, int cpu)
 
         if (IS_ERR(c_idle.idle))
                 panic("failed fork for CPU %d", cpu);
+
+        set_idle_for_cpu(cpu, c_idle.idle);
+
+do_rest:
         task_for_booting_cpu = c_idle.idle;
 
         Dprintk("Sending wakeup vector %lu to AP 0x%x/0x%x.\n", ap_wakeup_vector, cpu, sapicid);
 
+        set_brendez_area(cpu);
         platform_send_ipi(cpu, ap_wakeup_vector, IA64_IPI_DM_INT, 0);
 
         /*
@@ -555,16 +598,6 @@ void __devinit smp_prepare_boot_cpu(void)
 #ifdef CONFIG_HOTPLUG_CPU
 extern void fixup_irqs(void);
 /* must be called with cpucontrol mutex held */
-static int __devinit cpu_enable(unsigned int cpu)
-{
-        per_cpu(cpu_state,cpu) = CPU_UP_PREPARE;
-        wmb();
-
-        while (!cpu_online(cpu))
-                cpu_relax();
-        return 0;
-}
-
 int __cpu_disable(void)
 {
         int cpu = smp_processor_id();
@@ -577,7 +610,7 @@ int __cpu_disable(void)
 
         fixup_irqs();
         local_flush_tlb_all();
-        printk ("Disabled cpu %u\n", smp_processor_id());
+        cpu_clear(cpu, cpu_callin_map);
         return 0;
 }
 
@@ -589,12 +622,7 @@ void __cpu_die(unsigned int cpu)
                 /* They ack this in play_dead by setting CPU_DEAD */
                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
                 {
-                        /*
-                         * TBD: Enable this when physical removal
-                         * or when we put the processor is put in
-                         * SAL_BOOT_RENDEZ mode
-                         * cpu_clear(cpu, cpu_callin_map);
-                         */
+                        printk ("CPU %d is now offline\n", cpu);
                         return;
                 }
                 msleep(100);
@@ -602,11 +630,6 @@ void __cpu_die(unsigned int cpu)
         printk(KERN_ERR "CPU %u didn't die...\n", cpu);
 }
 #else /* !CONFIG_HOTPLUG_CPU */
-static int __devinit cpu_enable(unsigned int cpu)
-{
-        return 0;
-}
-
 int __cpu_disable(void)
 {
         return -ENOSYS;
@@ -648,16 +671,12 @@ __cpu_up (unsigned int cpu)
                 return -EINVAL;
 
         /*
-         * Already booted.. just enable and get outa idle lool
+         * Already booted cpu? not valid anymore since we dont
+         * do idle loop tightspin anymore.
          */
         if (cpu_isset(cpu, cpu_callin_map))
-        {
-                cpu_enable(cpu);
-                local_irq_enable();
-                while (!cpu_isset(cpu, cpu_online_map))
-                        mb();
-                return 0;
-        }
+                return -EINVAL;
+
         /* Processor goes to start_secondary(), sets online flag */
         ret = do_boot_cpu(sapicid, cpu);
         if (ret < 0)