4 files changed, 56 insertions, 17 deletions

diff --git a/arch/x86_64/kernel/genapic_flat.c b/arch/x86_64/kernel/genapic_flat.c
index b4cbbad04226..00f3fa6df714 100644
--- a/arch/x86_64/kernel/genapic_flat.c
+++ b/arch/x86_64/kernel/genapic_flat.c
@@ -7,6 +7,8 @@
  * Hacked for x86-64 by James Cleverdon from i386 architecture code by
  * Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
  * James Cleverdon.
+ * Ashok Raj <ashok.raj@intel.com>
+ *      Removed IPI broadcast shortcut to support CPU hotplug
  */
 #include <linux/config.h>
 #include <linux/threads.h>
@@ -45,22 +47,6 @@ static void flat_init_apic_ldr(void)
         apic_write_around(APIC_LDR, val);
 }
 
-static void flat_send_IPI_allbutself(int vector)
-{
-        /*
-         * if there are no other CPUs in the system then
-         * we get an APIC send error if we try to broadcast.
-         * thus we have to avoid sending IPIs in this case.
-         */
-        if (num_online_cpus() > 1)
-                __send_IPI_shortcut(APIC_DEST_ALLBUT, vector, APIC_DEST_LOGICAL);
-}
-
-static void flat_send_IPI_all(int vector)
-{
-        __send_IPI_shortcut(APIC_DEST_ALLINC, vector, APIC_DEST_LOGICAL);
-}
-
 static void flat_send_IPI_mask(cpumask_t cpumask, int vector)
 {
         unsigned long mask = cpus_addr(cpumask)[0];
@@ -93,6 +79,30 @@ static void flat_send_IPI_mask(cpumask_t cpumask, int vector)
         local_irq_restore(flags);
 }
 
+static void flat_send_IPI_allbutself(int vector)
+{
+        cpumask_t mask;
+        /*
+         * if there are no other CPUs in the system then
+         * we get an APIC send error if we try to broadcast.
+         * thus we have to avoid sending IPIs in this case.
+         */
+        int this_cpu = get_cpu();
+
+        mask = cpu_online_map;
+        cpu_clear(this_cpu, mask);
+
+        if (cpus_weight(mask) >= 1)
+                flat_send_IPI_mask(mask, vector);
+
+        put_cpu();
+}
+
+static void flat_send_IPI_all(int vector)
+{
+        flat_send_IPI_mask(cpu_online_map, vector);
+}
+
 static int flat_apic_id_registered(void)
 {
         return physid_isset(GET_APIC_ID(apic_read(APIC_ID)), phys_cpu_present_map);
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 1e379ed17b1d..ccae392886af 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -283,6 +283,16 @@ struct call_data_struct {
 
 static struct call_data_struct * call_data;
 
+void lock_ipi_call_lock(void)
+{
+        spin_lock_irq(&call_lock);
+}
+
+void unlock_ipi_call_lock(void)
+{
+        spin_unlock_irq(&call_lock);
+}
+
 /*
  * this function sends a 'generic call function' IPI to all other CPUs
  * in the system.
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index 571a55462fa0..b969ee128728 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -508,9 +508,22 @@ void __cpuinit start_secondary(void)
         set_cpu_sibling_map(smp_processor_id());
 
         /*
+         * We need to hold call_lock, so there is no inconsistency
+         * between the time smp_call_function() determines number of
+         * IPI receipients, and the time when the determination is made
+         * for which cpus receive the IPI in genapic_flat.c. Holding this
+         * lock helps us to not include this cpu in a currently in progress
+         * smp_call_function().
+         */
+        lock_ipi_call_lock();
+
+        /*
          * Allow the master to continue.
          */
         cpu_set(smp_processor_id(), cpu_online_map);
+        per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
+        unlock_ipi_call_lock();
+
         mb();
 
         /* Wait for TSC sync to not schedule things before.
@@ -1038,6 +1051,7 @@ void __init smp_prepare_boot_cpu(void)
         cpu_set(me, cpu_callout_map);
         cpu_set(0, cpu_sibling_map[0]);
         cpu_set(0, cpu_core_map[0]);
+        per_cpu(cpu_state, me) = CPU_ONLINE;
 }
 
 /*
@@ -1066,6 +1080,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
                 return -ENOSYS;
         }
 
+        per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
         /* Boot it! */
         err = do_boot_cpu(cpu, apicid);
         if (err < 0) {
@@ -1170,8 +1185,10 @@ void __cpu_die(unsigned int cpu)
 
         for (i = 0; i < 10; i++) {
                 /* They ack this in play_dead by setting CPU_DEAD */
-                if (per_cpu(cpu_state, cpu) == CPU_DEAD)
+                if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+                        printk ("CPU %d is now offline\n", cpu);
                         return;
+                }
                 current->state = TASK_UNINTERRUPTIBLE;
                 schedule_timeout(HZ/10);
         }
diff --git a/include/asm-x86_64/smp.h b/include/asm-x86_64/smp.h
index 9c6242fb99db..aeb1b73e21e1 100644
--- a/include/asm-x86_64/smp.h
+++ b/include/asm-x86_64/smp.h
@@ -43,6 +43,8 @@ extern cpumask_t cpu_callout_map;
 extern void smp_alloc_memory(void);
 extern volatile unsigned long smp_invalidate_needed;
 extern int pic_mode;
+extern void lock_ipi_call_lock(void);
+extern void unlock_ipi_call_lock(void);
 extern int smp_num_siblings;
 extern void smp_flush_tlb(void);
 extern void smp_message_irq(int cpl, void *dev_id, struct pt_regs *regs);