[IA64] add missing cpu_relax() in ITC syncing code

Call cpu_relax() in busy-waiting loops of the ITC-syncing code.

Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index ca1536db3394..dbc6b610cc64 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -1,7 +1,7 @@
 /*
  * SMP boot-related support
  *
- * Copyright (C) 1998-2003 Hewlett-Packard Co
+ * Copyright (C) 1998-2003, 2005 Hewlett-Packard Co
  *      David Mosberger-Tang <davidm@hpl.hp.com>
  *
  * 01/05/16 Rohit Seth <rohit.seth@intel.com>   Moved SMP booting functions from smp.c to here.
@@ -156,7 +156,8 @@ sync_master (void *arg)
         local_irq_save(flags);
         {
                 for (i = 0; i < NUM_ROUNDS*NUM_ITERS; ++i) {
-                        while (!go[MASTER]);
+                        while (!go[MASTER])
+                                cpu_relax();
                         go[MASTER] = 0;
                         go[SLAVE] = ia64_get_itc();
                 }
@@ -179,7 +180,8 @@ get_delta (long *rt, long *master)
         for (i = 0; i < NUM_ITERS; ++i) {
                 t0 = ia64_get_itc();
                 go[MASTER] = 1;
-                while (!(tm = go[SLAVE]));
+                while (!(tm = go[SLAVE]))
+                        cpu_relax();
                 go[SLAVE] = 0;
                 t1 = ia64_get_itc();
 
@@ -258,7 +260,8 @@ ia64_sync_itc (unsigned int master)
                 return;
         }
 
-        while (go[MASTER]);     /* wait for master to be ready */
+        while (go[MASTER])
+                cpu_relax();    /* wait for master to be ready */
 
         spin_lock_irqsave(&itc_sync_lock, flags);
         {