From cb1cc66d811dd558126bf98d1c05673cfc9745fa Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Fri, 23 Dec 2016 11:39:44 -0600
Subject: [PATCH] Implement deferred IRQ locking.  Adds partial support for
 Xtensa.  More is needed.

---
 arch/xtensa/src/common/xtensa_irqdispatch.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/xtensa/src/common/xtensa_irqdispatch.c b/arch/xtensa/src/common/xtensa_irqdispatch.c
index 813846e76e..be494df6e2 100644
--- a/arch/xtensa/src/common/xtensa_irqdispatch.c
+++ b/arch/xtensa/src/common/xtensa_irqdispatch.c
@@ -52,6 +52,7 @@
 
 #include "group/group.h"
 #include "sched/sched.h"
+#include "irq/irq.h"
 
 /****************************************************************************
  * Public Functions
@@ -129,6 +130,17 @@ uint32_t *xtensa_irq_dispatch(int irq, uint32_t *regs)
 
       (void)group_addrenv(NULL);
 #endif
+
+#ifdef CONFIG_SMP
+      /* In the SMP configuration, critical section management uses a
+       * "voting" algorithm with current task on each CPU casting its
+       * "vote" by the state of the TCB irqcount flag.  That irqcount
+       * for the current task on this CPU will be different is a
+       * context switch occurrred.
+       */
+
+      irq_restore_lock();
+#endif
     }
 #endif