From b05bce309031ba2fe7c7cd044af95e4ceb410fcb Mon Sep 17 00:00:00 2001
From: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>
Date: Fri, 30 Jul 2021 17:07:51 +0800
Subject: [PATCH] tzset: avoid taking semaphore in interrupt for non-kernel
 mode

Change-Id: Ic72819eddb38621751e462fe32e9e433288fb33c
Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>
---
 libs/libc/time/lib_localtime.c | 40 +++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/libs/libc/time/lib_localtime.c b/libs/libc/time/lib_localtime.c
index e94b6239fcd..fa01389a5d2 100644
--- a/libs/libc/time/lib_localtime.c
+++ b/libs/libc/time/lib_localtime.c
@@ -1817,19 +1817,28 @@ static FAR struct tm *localsub(FAR const time_t *timep,
 static FAR struct tm *gmtsub(FAR const time_t *timep,
                              int_fast32_t offset, FAR struct tm *tmp)
 {
-  tz_semtake(&g_gmt_sem);
-
   if (!g_gmt_isset)
     {
-      g_gmt_ptr = lib_malloc(sizeof *g_gmt_ptr);
-      if (g_gmt_ptr != NULL)
+#ifndef __KERNEL__
+      if (up_interrupt_context())
         {
-          gmtload(g_gmt_ptr);
-          g_gmt_isset = 1;
+          return NULL;
         }
-    }
+#endif
 
-  tz_semgive(&g_gmt_sem);
+      tz_semtake(&g_gmt_sem);
+      if (!g_gmt_isset)
+        {
+          g_gmt_ptr = lib_malloc(sizeof *g_gmt_ptr);
+          if (g_gmt_ptr != NULL)
+            {
+              gmtload(g_gmt_ptr);
+              g_gmt_isset = 1;
+            }
+        }
+
+      tz_semgive(&g_gmt_sem);
+    }
 
   tmp->tm_zone = GMT;
   return timesub(timep, offset, g_gmt_ptr, tmp);
@@ -2528,9 +2537,20 @@ void tzset(void)
 {
   FAR const char *name;
 
-  tz_semtake(&g_lcl_sem);
-
   name = getenv("TZ");
+  if (g_lcl_isset > 0 && name && strcmp(g_lcl_tzname, name) == 0)
+    {
+      return;
+    }
+
+#ifndef __KERNEL__
+  if (up_interrupt_context())
+    {
+      return;
+    }
+#endif
+
+  tz_semtake(&g_lcl_sem);
   if (name == NULL)
     {
       tzsetwall();