3 files changed, 54 insertions, 17 deletions

diff --git a/arch/x86_64/kernel/genapic_flat.c b/arch/x86_64/kernel/genapic_flat.c
index b4cbbad0422..00f3fa6df71 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 1e379ed17b1..ccae392886a 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 571a55462fa..b969ee12872 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);
 	}