SMP: Update some comments; trivial improvement by inlining static function.

arch/arm/src/armv7-a/arm_cpupause.c

@@ -59,7 +59,7 @@
  * up_cpu_pause().  The protocol for CPUn to pause CPUm is as follows
  *
  * 1. The up_cpu_pause() implementation on CPUn locks both g_cpu_wait[m]
- *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_wait[m].
+ *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_paused[m].
  * 2. CPUm receives the interrupt it (1) unlocks g_cpu_paused[m] and
  *    (2) locks g_cpu_wait[m].  The first unblocks CPUn and the second
  *    blocks CPUm in the interrupt handler.

arch/sim/src/up_internal.h

@@ -204,7 +204,7 @@ extern volatile int g_uart_data_available;
  * up_cpu_pause().  The protocol for CPUn to pause CPUm is as follows
  *
  * 1. The up_cpu_pause() implementation on CPUn locks both g_cpu_wait[m]
- *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_wait[m].
+ *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_paused[m].
  * 2. CPUm receives the interrupt it (1) unlocks g_cpu_paused[m] and
  *    (2) locks g_cpu_wait[m].  The first unblocks CPUn and the second
  *    blocks CPUm in the interrupt handler.

arch/sim/src/up_simsmp.c

@@ -83,7 +83,7 @@ static pthread_t              g_sim_cputhread[CONFIG_SMP_NCPUS];
  * up_cpu_pause().  The protocol for CPUn to pause CPUm is as follows
  *
  * 1. The up_cpu_pause() implementation on CPUn locks both g_cpu_wait[m]
- *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_wait[m].
+ *    and g_cpu_paused[m].  CPUn then waits spinning on g_cpu_paused[m].
  * 2. CPUm receives the interrupt it (1) unlocks g_cpu_paused[m] and
  *    (2) locks g_cpu_wait[m].  The first unblocks CPUn and the second
  *    blocks CPUm in the interrupt handler.

sched/irq/irq_csection.c

@@ -104,10 +104,8 @@ static uint8_t g_cpu_nestcount[CONFIG_SMP_NCPUS];
  ****************************************************************************/
 
 #ifdef CONFIG_SMP
-static void irq_waitlock(void)
+static inline void irq_waitlock(int cpu)
 {
-  int cpu = this_cpu();
-
   /* Duplicate the spin_lock() logic from spinlock.c, but adding the check
    * for the deadlock condition.
    */
@@ -262,10 +260,10 @@ irqstate_t enter_critical_section(void)
               if ((g_cpu_irqset & (1 << cpu)) == 0)
                 {
                   /* Wait until we can get the spinlock (meaning that we are
-                   * no longer in the critical section).
+                   * no longer blocked by the critical section).
                    */
 
-                  irq_waitlock();
+                  irq_waitlock(cpu);
                 }
 
               /* In any event, the nesting count is now one */