smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

While trying to initialize idle threads for all cpus, idle_threads_init()
calls smp_processor_id() in a loop, which is unnecessary. The intent
is to initialize idle threads for all non-boot cpus. So just use a variable
to note the boot cpu and use it in the loop.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: suresh.b.siddha@intel.com
Cc: venki@google.com
Cc: nikunj@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20120524151055.2549.64309.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index e1a797e028a3..0f2162f808a7 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -52,10 +52,12 @@ static inline void idle_init(unsigned int cpu)
  */
 void __init idle_threads_init(void)
 {
-        unsigned int cpu;
+        unsigned int cpu, boot_cpu;
+
+        boot_cpu = smp_processor_id();
 
         for_each_possible_cpu(cpu) {
-                if (cpu != smp_processor_id())
+                if (cpu != boot_cpu)
                         idle_init(cpu);
         }
 }