Merged in masayuki2009/nuttx.nuttx/smp_fixes (pull request #561)

SMP fixes

Approved-by: Gregory Nutt <gnutt@nuttx.org>

arch/arm/src/lc823450/lc823450_testset.c

@@ -95,12 +95,15 @@ spinlock_t up_testset(volatile FAR spinlock_t *lock)
     }
   while (getreg32(MUTEX_REG_MUTEX0) != val);
 
+  SP_DMB();
+
   ret = *lock;
 
   if (ret == SP_UNLOCKED)
     {
       *lock = SP_LOCKED;
     }
+  SP_DMB();
 
   val = (up_cpu_index() << 16) | 0x0;
   putreg32(val, MUTEX_REG_MUTEX0);

sched/semaphore/spinlock.c

@@ -165,8 +165,9 @@ void spin_unlock(FAR volatile spinlock_t *lock)
   sched_note_spinunlock(this_task(), lock);
 #endif
 
-  *lock = SP_UNLOCKED;
   SP_DMB();
+  *lock = SP_UNLOCKED;
+  SP_DSB();
 }
 #endif