From 7572b6866844b1cc81014bd51715447dde893e2d Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Fri, 26 Feb 2021 17:00:14 +0800
Subject: [PATCH 01/10] fix race

Signed-off-by: Song Gao <disxiaofei@163.com>
---
 config/config_util_test.go     | 17 ++++++++++++++---
 ddl/placement_sql_test.go      | 16 ++++++++--------
 executor/executor_test.go      |  8 ++++----
 expression/integration_test.go |  8 ++++----
 session/session_test.go        | 19 +++++++++++--------
 5 files changed, 41 insertions(+), 27 deletions(-)

diff --git a/config/config_util_test.go b/config/config_util_test.go
index 2b2056a309415..1cbd850bbc543 100644
--- a/config/config_util_test.go
+++ b/config/config_util_test.go
@@ -170,16 +170,27 @@ engines = ["tikv", "tiflash", "tidb"]
 }
 
 func (s *testConfigSuite) TestTxnScopeValue(c *C) {
-	GetGlobalConfig().Labels["zone"] = "bj"
+	defer RestoreFunc()
+	UpdateGlobal(func(conf *Config) {
+		conf.Labels["zone"] = "bj"
+	})
 	isGlobal, v := GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsFalse)
 	c.Assert(v, Equals, "bj")
-	GetGlobalConfig().Labels["zone"] = ""
+	UpdateGlobal(func(conf *Config) {
+		conf.Labels["zone"] = ""
+	})
 	isGlobal, v = GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsTrue)
 	c.Assert(v, Equals, "global")
-	GetGlobalConfig().Labels["zone"] = "global"
+	UpdateGlobal(func(conf *Config) {
+		conf.Labels["zone"] = "global"
+	})
 	isGlobal, v = GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsFalse)
 	c.Assert(v, Equals, "global")
 }
+
+func SetLabelConfig() {
+	GetGlobalConfig()
+}
diff --git a/ddl/placement_sql_test.go b/ddl/placement_sql_test.go
index 9c98942653b97..56694e97a42f5 100644
--- a/ddl/placement_sql_test.go
+++ b/ddl/placement_sql_test.go
@@ -441,7 +441,7 @@ func (s *testDBSuite1) TestPlacementPolicyCache(c *C) {
 
 func (s *testSerialDBSuite) TestTxnScopeConstraint(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
@@ -569,9 +569,9 @@ PARTITION BY RANGE (c) (
 
 	for _, testcase := range testCases {
 		c.Log(testcase.name)
-		config.GetGlobalConfig().Labels = map[string]string{
-			"zone": testcase.zone,
-		}
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels["zone"] = testcase.zone
+		})
 		se, err := session.CreateSession4Test(s.store)
 		c.Check(err, IsNil)
 		tk.Se = se
@@ -662,7 +662,7 @@ add placement policy
 
 func (s *testSerialSuite) TestGlobalTxnState(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
@@ -704,9 +704,9 @@ PARTITION BY RANGE (c) (
 			},
 		},
 	}
-	config.GetGlobalConfig().Labels = map[string]string{
-		"zone": "bj",
-	}
+	config.UpdateGlobal(func(conf *config.Config) {
+		conf.Labels["zone"] = "bj"
+	})
 	dbInfo := testGetSchemaByName(c, tk.Se, "test")
 	tk2 := testkit.NewTestKit(c, s.store)
 	var chkErr error
diff --git a/executor/executor_test.go b/executor/executor_test.go
index d672f45cc9438..4772423925b06 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -7480,7 +7480,7 @@ func (s *testSuite) TestIssue15563(c *C) {
 
 func (s *testSerialSuite) TestStalenessTransaction(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
 	c.Assert(failpoint.Enable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer", "return(false)"), IsNil)
 	defer failpoint.Disable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer")
@@ -7543,9 +7543,9 @@ func (s *testSerialSuite) TestStalenessTransaction(c *C) {
 	tk.MustExec("use test")
 	for _, testcase := range testcases {
 		c.Log(testcase.name)
-		config.GetGlobalConfig().Labels = map[string]string{
-			"zone": testcase.zone,
-		}
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels["zone"] = testcase.zone
+		})
 		tk.MustExec(fmt.Sprintf("set @@txn_scope=%v", testcase.txnScope))
 		tk.MustExec(testcase.preSQL)
 		tk.MustExec(testcase.sql)
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 189efa4a16826..cdc720be6322c 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -8539,7 +8539,7 @@ func (s *testIntegrationSuite) TestIssue12209(c *C) {
 
 func (s *testIntegrationSerialSuite) TestCrossDCQuery(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
@@ -8656,9 +8656,9 @@ PARTITION BY RANGE (c) (
 	}
 	for _, testcase := range testcases {
 		c.Log(testcase.name)
-		config.GetGlobalConfig().Labels = map[string]string{
-			"zone": testcase.zone,
-		}
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels["zone"] = testcase.zone
+		})
 		_, err = tk.Exec(fmt.Sprintf("set @@txn_scope='%v'", testcase.txnScope))
 		c.Assert(err, IsNil)
 		res, err := tk.Exec(testcase.sql)
diff --git a/session/session_test.go b/session/session_test.go
index 83c660c9edfe4..5e86f404d1896 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3257,9 +3257,11 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
-	config.GetGlobalConfig().Labels["zone"] = ""
+	config.UpdateGlobal(func(conf *config.Config) {
+		conf.Labels["zone"] = ""
+	})
 	tk := testkit.NewTestKitWithInit(c, s.store)
 	// assert default value
 	result := tk.MustQuery("select @@txn_scope;")
@@ -3270,8 +3272,9 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 	result = tk.MustQuery("select @@txn_scope;")
 	result.Check(testkit.Rows(oracle.GlobalTxnScope))
 	c.Assert(tk.Se.GetSessionVars().CheckAndGetTxnScope(), Equals, oracle.GlobalTxnScope)
-
-	config.GetGlobalConfig().Labels["zone"] = "bj"
+	config.UpdateGlobal(func(conf *config.Config) {
+		conf.Labels["zone"] = "bj"
+	})
 	tk = testkit.NewTestKitWithInit(c, s.store)
 	// assert default value
 	result = tk.MustQuery("select @@txn_scope;")
@@ -3291,7 +3294,7 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 
 func (s *testSessionSerialSuite) TestGlobalAndLocalTxn(c *C) {
 	defer func() {
-		config.GetGlobalConfig().Labels["zone"] = ""
+		config.RestoreFunc()
 	}()
 	// Because the PD config of check_dev_2 test is not compatible with local/global txn yet,
 	// so we will skip this test for now.
@@ -3382,9 +3385,9 @@ PARTITION BY RANGE (c) (
 	result = tk.MustQuery("select * from t1")      // read dc-1 and dc-2 with global scope
 	c.Assert(len(result.Rows()), Equals, 3)
 
-	config.GetGlobalConfig().Labels = map[string]string{
-		"zone": "dc-1",
-	}
+	config.UpdateGlobal(func(conf *config.Config) {
+		conf.Labels["zone"] = "dc-1"
+	})
 	// set txn_scope to local
 	tk.MustExec("set @@session.txn_scope = 'local';")
 	result = tk.MustQuery("select @@txn_scope;")

From 609267a361db0c0fbc8d89f5d28798da701fda6c Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Fri, 26 Feb 2021 17:28:22 +0800
Subject: [PATCH 02/10] fix lint

Signed-off-by: Song Gao <disxiaofei@163.com>
---
 config/config_util_test.go | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/config/config_util_test.go b/config/config_util_test.go
index 1cbd850bbc543..d047689adf4ef 100644
--- a/config/config_util_test.go
+++ b/config/config_util_test.go
@@ -190,7 +190,3 @@ func (s *testConfigSuite) TestTxnScopeValue(c *C) {
 	c.Assert(isGlobal, IsFalse)
 	c.Assert(v, Equals, "global")
 }
-
-func SetLabelConfig() {
-	GetGlobalConfig()
-}

From c17888733e24a78a8023fcd9e84b6cfabe9b8b6a Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Fri, 26 Feb 2021 17:56:15 +0800
Subject: [PATCH 03/10] address the comment

Signed-off-by: Song Gao <disxiaofei@163.com>
---
 ddl/placement_sql_test.go      | 8 ++------
 executor/executor_test.go      | 4 +---
 expression/integration_test.go | 4 +---
 session/session_test.go        | 8 ++------
 4 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/ddl/placement_sql_test.go b/ddl/placement_sql_test.go
index 56694e97a42f5..b9fad55c06d64 100644
--- a/ddl/placement_sql_test.go
+++ b/ddl/placement_sql_test.go
@@ -440,9 +440,7 @@ func (s *testDBSuite1) TestPlacementPolicyCache(c *C) {
 }
 
 func (s *testSerialDBSuite) TestTxnScopeConstraint(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
@@ -661,9 +659,7 @@ add placement policy
 }
 
 func (s *testSerialSuite) TestGlobalTxnState(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/executor/executor_test.go b/executor/executor_test.go
index 4772423925b06..df7cc322dbf1a 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -7479,9 +7479,7 @@ func (s *testSuite) TestIssue15563(c *C) {
 }
 
 func (s *testSerialSuite) TestStalenessTransaction(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	c.Assert(failpoint.Enable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer", "return(false)"), IsNil)
 	defer failpoint.Disable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer")
 	testcases := []struct {
diff --git a/expression/integration_test.go b/expression/integration_test.go
index cdc720be6322c..079a1d5c0bb8f 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -8538,9 +8538,7 @@ func (s *testIntegrationSuite) TestIssue12209(c *C) {
 }
 
 func (s *testIntegrationSerialSuite) TestCrossDCQuery(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/session/session_test.go b/session/session_test.go
index 5e86f404d1896..d5a6933716b35 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3256,9 +3256,7 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	config.UpdateGlobal(func(conf *config.Config) {
 		conf.Labels["zone"] = ""
 	})
@@ -3293,9 +3291,7 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestGlobalAndLocalTxn(c *C) {
-	defer func() {
-		config.RestoreFunc()
-	}()
+	defer config.RestoreFunc()
 	// Because the PD config of check_dev_2 test is not compatible with local/global txn yet,
 	// so we will skip this test for now.
 	if *withTiKV {

From 637dfb65d9034f35297a4a8b625aa0c85f3ed092 Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 11:41:58 +0800
Subject: [PATCH 04/10] fix test

---
 config/config_util_test.go     | 2 +-
 ddl/placement_sql_test.go      | 4 ++--
 executor/executor_test.go      | 2 +-
 expression/integration_test.go | 2 +-
 session/session_test.go        | 4 ++--
 5 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/config/config_util_test.go b/config/config_util_test.go
index d047689adf4ef..5d45589c06d88 100644
--- a/config/config_util_test.go
+++ b/config/config_util_test.go
@@ -170,7 +170,7 @@ engines = ["tikv", "tiflash", "tidb"]
 }
 
 func (s *testConfigSuite) TestTxnScopeValue(c *C) {
-	defer RestoreFunc()
+	defer RestoreFunc()()
 	UpdateGlobal(func(conf *Config) {
 		conf.Labels["zone"] = "bj"
 	})
diff --git a/ddl/placement_sql_test.go b/ddl/placement_sql_test.go
index b9fad55c06d64..2601a88b59e34 100644
--- a/ddl/placement_sql_test.go
+++ b/ddl/placement_sql_test.go
@@ -440,7 +440,7 @@ func (s *testDBSuite1) TestPlacementPolicyCache(c *C) {
 }
 
 func (s *testSerialDBSuite) TestTxnScopeConstraint(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
@@ -659,7 +659,7 @@ add placement policy
 }
 
 func (s *testSerialSuite) TestGlobalTxnState(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/executor/executor_test.go b/executor/executor_test.go
index df7cc322dbf1a..8595b6ce01323 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -7479,7 +7479,7 @@ func (s *testSuite) TestIssue15563(c *C) {
 }
 
 func (s *testSerialSuite) TestStalenessTransaction(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	c.Assert(failpoint.Enable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer", "return(false)"), IsNil)
 	defer failpoint.Disable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer")
 	testcases := []struct {
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 079a1d5c0bb8f..706f71adcb169 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -8538,7 +8538,7 @@ func (s *testIntegrationSuite) TestIssue12209(c *C) {
 }
 
 func (s *testIntegrationSerialSuite) TestCrossDCQuery(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/session/session_test.go b/session/session_test.go
index d5a6933716b35..c31c0716b96e9 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3256,7 +3256,7 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	config.UpdateGlobal(func(conf *config.Config) {
 		conf.Labels["zone"] = ""
 	})
@@ -3291,7 +3291,7 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestGlobalAndLocalTxn(c *C) {
-	defer config.RestoreFunc()
+	defer config.RestoreFunc()()
 	// Because the PD config of check_dev_2 test is not compatible with local/global txn yet,
 	// so we will skip this test for now.
 	if *withTiKV {

From 5b00a48f4670c7ba0f7020554c8b09a51ef0252a Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 11:54:24 +0800
Subject: [PATCH 05/10] fix test

Signed-off-by: Song Gao <disxiaofei@163.com>
---
 config/config_util_test.go     |  6 +++++-
 ddl/placement_sql_test.go      | 12 ++++++++++--
 executor/executor_test.go      |  6 +++++-
 expression/integration_test.go |  6 +++++-
 session/session_test.go        | 12 ++++++++++--
 5 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/config/config_util_test.go b/config/config_util_test.go
index 5d45589c06d88..5fa6212791931 100644
--- a/config/config_util_test.go
+++ b/config/config_util_test.go
@@ -170,7 +170,11 @@ engines = ["tikv", "tiflash", "tidb"]
 }
 
 func (s *testConfigSuite) TestTxnScopeValue(c *C) {
-	defer RestoreFunc()()
+	defer func() {
+		UpdateGlobal(func(conf *Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	UpdateGlobal(func(conf *Config) {
 		conf.Labels["zone"] = "bj"
 	})
diff --git a/ddl/placement_sql_test.go b/ddl/placement_sql_test.go
index 2601a88b59e34..a322462999d6f 100644
--- a/ddl/placement_sql_test.go
+++ b/ddl/placement_sql_test.go
@@ -440,7 +440,11 @@ func (s *testDBSuite1) TestPlacementPolicyCache(c *C) {
 }
 
 func (s *testSerialDBSuite) TestTxnScopeConstraint(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
@@ -659,7 +663,11 @@ add placement policy
 }
 
 func (s *testSerialSuite) TestGlobalTxnState(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/executor/executor_test.go b/executor/executor_test.go
index 8595b6ce01323..0bc8ba40e6dcc 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -7479,7 +7479,11 @@ func (s *testSuite) TestIssue15563(c *C) {
 }
 
 func (s *testSerialSuite) TestStalenessTransaction(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	c.Assert(failpoint.Enable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer", "return(false)"), IsNil)
 	defer failpoint.Disable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer")
 	testcases := []struct {
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 706f71adcb169..7620f7c6a6156 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -8538,7 +8538,11 @@ func (s *testIntegrationSuite) TestIssue12209(c *C) {
 }
 
 func (s *testIntegrationSerialSuite) TestCrossDCQuery(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
diff --git a/session/session_test.go b/session/session_test.go
index 32c15a32c706a..acab83bc3724f 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3256,7 +3256,11 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	config.UpdateGlobal(func(conf *config.Config) {
 		conf.Labels["zone"] = ""
 	})
@@ -3291,7 +3295,11 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestGlobalAndLocalTxn(c *C) {
-	defer config.RestoreFunc()()
+	defer func() {
+		config.UpdateGlobal(func(conf *config.Config) {
+			conf.Labels = map[string]string{}
+		})
+	}()
 	// Because the PD config of check_dev_2 test is not compatible with local/global txn yet,
 	// so we will skip this test for now.
 	if *withTiKV {

From 47e3e38cd0d56671d1f2c142fea41daf26cac427 Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 14:37:20 +0800
Subject: [PATCH 06/10] fix race test

Signed-off-by: Song Gao <disxiaofei@163.com>
---
 config/config_util.go          |  8 ++++++++
 config/config_util_test.go     | 21 +++++++--------------
 ddl/placement_sql_test.go      | 23 ++++++-----------------
 executor/executor_test.go      | 11 +++--------
 expression/integration_test.go |  7 ++++---
 session/session_test.go        | 15 ++++-----------
 6 files changed, 32 insertions(+), 53 deletions(-)

diff --git a/config/config_util.go b/config/config_util.go
index 6018359802b5d..ce54255369507 100644
--- a/config/config_util.go
+++ b/config/config_util.go
@@ -25,6 +25,7 @@ import (
 
 	"github.com/BurntSushi/toml"
 	"github.com/pingcap/errors"
+	"github.com/pingcap/failpoint"
 )
 
 // CloneConf deeply clones this config.
@@ -161,6 +162,13 @@ const (
 
 // GetTxnScopeFromConfig extracts @@txn_scope value from config
 func GetTxnScopeFromConfig() (bool, string) {
+	failpoint.Inject("injectTxnScope", func(val failpoint.Value) {
+		v := val.(string)
+		if len(v) > 0 {
+			failpoint.Return(false, v)
+		}
+		failpoint.Return(true, globalTxnScope)
+	})
 	v, ok := GetGlobalConfig().Labels["zone"]
 	if ok && len(v) > 0 {
 		return false, v
diff --git a/config/config_util_test.go b/config/config_util_test.go
index 5fa6212791931..3ed621758f757 100644
--- a/config/config_util_test.go
+++ b/config/config_util_test.go
@@ -23,6 +23,7 @@ import (
 
 	"github.com/BurntSushi/toml"
 	. "github.com/pingcap/check"
+	"github.com/pingcap/failpoint"
 )
 
 func (s *testConfigSuite) TestCloneConf(c *C) {
@@ -170,27 +171,19 @@ engines = ["tikv", "tiflash", "tidb"]
 }
 
 func (s *testConfigSuite) TestTxnScopeValue(c *C) {
-	defer func() {
-		UpdateGlobal(func(conf *Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
-	UpdateGlobal(func(conf *Config) {
-		conf.Labels["zone"] = "bj"
-	})
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("bj")`)
 	isGlobal, v := GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsFalse)
 	c.Assert(v, Equals, "bj")
-	UpdateGlobal(func(conf *Config) {
-		conf.Labels["zone"] = ""
-	})
+	failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("")`)
 	isGlobal, v = GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsTrue)
 	c.Assert(v, Equals, "global")
-	UpdateGlobal(func(conf *Config) {
-		conf.Labels["zone"] = "global"
-	})
+	failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("global")`)
 	isGlobal, v = GetTxnScopeFromConfig()
 	c.Assert(isGlobal, IsFalse)
 	c.Assert(v, Equals, "global")
+	failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 }
diff --git a/ddl/placement_sql_test.go b/ddl/placement_sql_test.go
index a322462999d6f..91c48528a986a 100644
--- a/ddl/placement_sql_test.go
+++ b/ddl/placement_sql_test.go
@@ -18,8 +18,8 @@ import (
 	"sort"
 
 	. "github.com/pingcap/check"
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/parser/model"
-	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/ddl/placement"
 	"github.com/pingcap/tidb/session"
@@ -440,11 +440,6 @@ func (s *testDBSuite1) TestPlacementPolicyCache(c *C) {
 }
 
 func (s *testSerialDBSuite) TestTxnScopeConstraint(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
@@ -571,9 +566,8 @@ PARTITION BY RANGE (c) (
 
 	for _, testcase := range testCases {
 		c.Log(testcase.name)
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels["zone"] = testcase.zone
-		})
+		failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",
+			fmt.Sprintf(`return("%v")`, testcase.zone))
 		se, err := session.CreateSession4Test(s.store)
 		c.Check(err, IsNil)
 		tk.Se = se
@@ -593,6 +587,7 @@ PARTITION BY RANGE (c) (
 			c.Assert(err, NotNil)
 			c.Assert(err.Error(), Matches, testcase.err.Error())
 		}
+		failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	}
 }
 
@@ -663,11 +658,6 @@ add placement policy
 }
 
 func (s *testSerialSuite) TestGlobalTxnState(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")
@@ -708,9 +698,8 @@ PARTITION BY RANGE (c) (
 			},
 		},
 	}
-	config.UpdateGlobal(func(conf *config.Config) {
-		conf.Labels["zone"] = "bj"
-	})
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("bj")`)
+	defer failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	dbInfo := testGetSchemaByName(c, tk.Se, "test")
 	tk2 := testkit.NewTestKit(c, s.store)
 	var chkErr error
diff --git a/executor/executor_test.go b/executor/executor_test.go
index 6b3abfe8793aa..e47a122fce543 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -7480,11 +7480,6 @@ func (s *testSuite) TestIssue15563(c *C) {
 }
 
 func (s *testSerialSuite) TestStalenessTransaction(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
 	c.Assert(failpoint.Enable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer", "return(false)"), IsNil)
 	defer failpoint.Disable("github.com/pingcap/tidb/executor/mockStalenessTxnSchemaVer")
 	testcases := []struct {
@@ -7546,9 +7541,8 @@ func (s *testSerialSuite) TestStalenessTransaction(c *C) {
 	tk.MustExec("use test")
 	for _, testcase := range testcases {
 		c.Log(testcase.name)
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels["zone"] = testcase.zone
-		})
+		failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",
+			fmt.Sprintf(`return("%v")`, testcase.zone))
 		tk.MustExec(fmt.Sprintf("set @@txn_scope=%v", testcase.txnScope))
 		tk.MustExec(testcase.preSQL)
 		tk.MustExec(testcase.sql)
@@ -7567,6 +7561,7 @@ func (s *testSerialSuite) TestStalenessTransaction(c *C) {
 		}
 		c.Assert(tk.Se.GetSessionVars().TxnCtx.IsStaleness, Equals, testcase.IsStaleness)
 		tk.MustExec("commit")
+		failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	}
 }
 
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 7620f7c6a6156..edd1f97306cba 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -26,6 +26,7 @@ import (
 
 	. "github.com/pingcap/check"
 	"github.com/pingcap/errors"
+	"github.com/pingcap/failpoint"
 	"github.com/pingcap/parser/auth"
 	"github.com/pingcap/parser/model"
 	"github.com/pingcap/parser/mysql"
@@ -8658,9 +8659,8 @@ PARTITION BY RANGE (c) (
 	}
 	for _, testcase := range testcases {
 		c.Log(testcase.name)
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels["zone"] = testcase.zone
-		})
+		failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",
+			fmt.Sprintf(`return("%v")`, testcase.zone))
 		_, err = tk.Exec(fmt.Sprintf("set @@txn_scope='%v'", testcase.txnScope))
 		c.Assert(err, IsNil)
 		res, err := tk.Exec(testcase.sql)
@@ -8677,6 +8677,7 @@ PARTITION BY RANGE (c) (
 		} else {
 			c.Assert(checkErr, IsNil)
 		}
+		failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	}
 }
 
diff --git a/session/session_test.go b/session/session_test.go
index 04785e079562d..801e514236511 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3257,14 +3257,7 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
-	config.UpdateGlobal(func(conf *config.Config) {
-		conf.Labels["zone"] = ""
-	})
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",`return("")`)
 	tk := testkit.NewTestKitWithInit(c, s.store)
 	// assert default value
 	result := tk.MustQuery("select @@txn_scope;")
@@ -3275,9 +3268,9 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 	result = tk.MustQuery("select @@txn_scope;")
 	result.Check(testkit.Rows(oracle.GlobalTxnScope))
 	c.Assert(tk.Se.GetSessionVars().CheckAndGetTxnScope(), Equals, oracle.GlobalTxnScope)
-	config.UpdateGlobal(func(conf *config.Config) {
-		conf.Labels["zone"] = "bj"
-	})
+	failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",`return("bj")`)
+	defer failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	tk = testkit.NewTestKitWithInit(c, s.store)
 	// assert default value
 	result = tk.MustQuery("select @@txn_scope;")

From 2ef2859bcc41e98df19065b1265b722cf718113d Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 14:40:59 +0800
Subject: [PATCH 07/10] make fmt

---
 session/session_test.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/session/session_test.go b/session/session_test.go
index 801e514236511..e9a9a0e538f2d 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3257,7 +3257,7 @@ func (s *testSessionSuite2) TestPerStmtTaskID(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
-	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",`return("")`)
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("")`)
 	tk := testkit.NewTestKitWithInit(c, s.store)
 	// assert default value
 	result := tk.MustQuery("select @@txn_scope;")
@@ -3269,7 +3269,7 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 	result.Check(testkit.Rows(oracle.GlobalTxnScope))
 	c.Assert(tk.Se.GetSessionVars().CheckAndGetTxnScope(), Equals, oracle.GlobalTxnScope)
 	failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
-	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope",`return("bj")`)
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("bj")`)
 	defer failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	tk = testkit.NewTestKitWithInit(c, s.store)
 	// assert default value

From d60e4ee109838a34ebc03fa69480a716ef0dc432 Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 15:00:42 +0800
Subject: [PATCH 08/10] Update session_test.go

---
 session/session_test.go | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/session/session_test.go b/session/session_test.go
index e9a9a0e538f2d..124d7e4db4406 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -3289,11 +3289,6 @@ func (s *testSessionSerialSuite) TestSetTxnScope(c *C) {
 }
 
 func (s *testSessionSerialSuite) TestGlobalAndLocalTxn(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
 	// Because the PD config of check_dev_2 test is not compatible with local/global txn yet,
 	// so we will skip this test for now.
 	if *withTiKV {
@@ -3383,9 +3378,8 @@ PARTITION BY RANGE (c) (
 	result = tk.MustQuery("select * from t1")      // read dc-1 and dc-2 with global scope
 	c.Assert(len(result.Rows()), Equals, 3)
 
-	config.UpdateGlobal(func(conf *config.Config) {
-		conf.Labels["zone"] = "dc-1"
-	})
+	failpoint.Enable("github.com/pingcap/tidb/config/injectTxnScope", `return("dc-1")`)
+	defer failpoint.Disable("github.com/pingcap/tidb/config/injectTxnScope")
 	// set txn_scope to local
 	tk.MustExec("set @@session.txn_scope = 'local';")
 	result = tk.MustQuery("select @@txn_scope;")

From 898adb2fd644f00fd6cc602b0a6dd219214d52d4 Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 15:04:17 +0800
Subject: [PATCH 09/10] Update integration_test.go

---
 expression/integration_test.go | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/expression/integration_test.go b/expression/integration_test.go
index edd1f97306cba..77b9ee6d060f4 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -8539,11 +8539,6 @@ func (s *testIntegrationSuite) TestIssue12209(c *C) {
 }
 
 func (s *testIntegrationSerialSuite) TestCrossDCQuery(c *C) {
-	defer func() {
-		config.UpdateGlobal(func(conf *config.Config) {
-			conf.Labels = map[string]string{}
-		})
-	}()
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t1")

From e484fec13953689dba062f223cb6e9ccc53503eb Mon Sep 17 00:00:00 2001
From: Song Gao <disxiaofei@163.com>
Date: Mon, 1 Mar 2021 15:07:09 +0800
Subject: [PATCH 10/10] make vet

---
 expression/integration_test.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/expression/integration_test.go b/expression/integration_test.go
index 77b9ee6d060f4..bd0b8e673e250 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -31,7 +31,6 @@ import (
 	"github.com/pingcap/parser/model"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/parser/terror"
-	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl/placement"
 	"github.com/pingcap/tidb/domain"
 	"github.com/pingcap/tidb/expression"