2 files changed, 75 insertions, 9 deletions

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 6ee74db..e595822 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -293,6 +293,69 @@ void unlock_ipi_call_lock(void)
 }
 
 /*
+ * this function sends a 'generic call function' IPI to one other CPU
+ * in the system.
+ */
+static void __smp_call_function_single (int cpu, void (*func) (void *info), void *info,
+				int nonatomic, int wait)
+{
+	struct call_data_struct data;
+	int cpus = 1;
+
+	data.func = func;
+	data.info = info;
+	atomic_set(&data.started, 0);
+	data.wait = wait;
+	if (wait)
+		atomic_set(&data.finished, 0);
+
+	call_data = &data;
+	wmb();
+	/* Send a message to all other CPUs and wait for them to respond */
+	send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR);
+
+	/* Wait for response */
+	while (atomic_read(&data.started) != cpus)
+		cpu_relax();
+
+	if (!wait)
+		return;
+
+	while (atomic_read(&data.finished) != cpus)
+		cpu_relax();
+}
+
+/*
+ * smp_call_function_single - Run a function on another CPU
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @nonatomic: Currently unused.
+ * @wait: If true, wait until function has completed on other CPUs.
+ *
+ * Retrurns 0 on success, else a negative status code.
+ *
+ * Does not return until the remote CPU is nearly ready to execute <func>
+ * or is or has executed.
+ */
+
+int smp_call_function_single (int cpu, void (*func) (void *info), void *info,
+	int nonatomic, int wait)
+{
+	/* prevent preemption and reschedule on another processor */
+	int me = get_cpu();
+	if (cpu == me) {
+		WARN_ON(1);
+		put_cpu();
+		return -EBUSY;
+	}
+	spin_lock_bh(&call_lock);
+	__smp_call_function_single(cpu, func, info, nonatomic, wait);
+	spin_unlock_bh(&call_lock);
+	put_cpu();
+	return 0;
+}
+
+/*
  * 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 6d23354..6e4807d 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -211,9 +211,6 @@ static __cpuinit void sync_master(void *arg)
 {
 	unsigned long flags, i;
 
-	if (smp_processor_id() != 0)
-		return;
-
 	go[MASTER] = 0;
 
 	local_irq_save(flags);
@@ -262,7 +259,7 @@ get_delta(long *rt, long *master)
 	return tcenter - best_tm;
 }
 
-static __cpuinit void sync_tsc(void)
+static __cpuinit void sync_tsc(unsigned int master)
 {
 	int i, done = 0;
 	long delta, adj, adjust_latency = 0;
@@ -276,9 +273,17 @@ static __cpuinit void sync_tsc(void)
 	} t[NUM_ROUNDS] __cpuinitdata;
 #endif
 
+	printk(KERN_INFO "CPU %d: Syncing TSC to CPU %u.\n",
+		smp_processor_id(), master);
+
 	go[MASTER] = 1;
 
-	smp_call_function(sync_master, NULL, 1, 0);
+	/* It is dangerous to broadcast IPI as cpus are coming up,
+	 * as they may not be ready to accept them.  So since
+	 * we only need to send the ipi to the boot cpu direct
+	 * the message, and avoid the race.
+	 */
+	smp_call_function_single(master, sync_master, NULL, 1, 0);
 
 	while (go[MASTER])	/* wait for master to be ready */
 		no_cpu_relax();
@@ -322,16 +327,14 @@ static __cpuinit void sync_tsc(void)
 	printk(KERN_INFO
 	       "CPU %d: synchronized TSC with CPU %u (last diff %ld cycles, "
 	       "maxerr %lu cycles)\n",
-	       smp_processor_id(), boot_cpu_id, delta, rt);
+	       smp_processor_id(), master, delta, rt);
 }
 
 static void __cpuinit tsc_sync_wait(void)
 {
 	if (notscsync || !cpu_has_tsc)
 		return;
-	printk(KERN_INFO "CPU %d: Syncing TSC to CPU %u.\n", smp_processor_id(),
-			boot_cpu_id);
-	sync_tsc();
+	sync_tsc(boot_cpu_id);
 }
 
 static __init int notscsync_setup(char *s)