data race in the GlobalConfig

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

 WARNING: DATA RACE
Write at 0x00c0095f6840 by goroutine 192:
  github.com/pingcap/tidb/sessionctx/variable.glob..func226()
      /go/tidb/sessionctx/variable/sysvar.go:1621 +0xa4
  github.com/pingcap/tidb/sessionctx/variable.(*SysVar).SetSessionFromHook()
      /go/tidb/sessionctx/variable/sysvar.go:199 +0xaf
  github.com/pingcap/tidb/sessionctx/variable.(*SessionVars).SetSystemVar()
      /go/tidb/sessionctx/variable/session.go:1588 +0x59
  github.com/pingcap/tidb/executor.loadVariables()
      /go/tidb/executor/plan_replayer.go:544 +0x70d
  github.com/pingcap/tidb/executor.(*PlanReplayerLoadInfo).Update()
      /go/tidb/executor/plan_replayer.go:618 +0x137
  github.com/pingcap/tidb/server.(*clientConn).handlePlanReplayerLoad()
      /go/tidb/server/conn.go:1742 +0xd7
  github.com/pingcap/tidb/server.(*clientConn).handleQuerySpecial()
      /go/tidb/server/conn.go:2024 +0x6cd
  github.com/pingcap/tidb/server.(*clientConn).handleStmt()
      /go/tidb/server/conn.go:1978 +0x5a8
  github.com/pingcap/tidb/server.(*clientConn).handleQuery()
      /go/tidb/server/conn.go:1819 +0x97c
  github.com/pingcap/tidb/server.(*clientConn).dispatch()
      /go/tidb/server/conn.go:1324 +0x1228
  github.com/pingcap/tidb/server.(*clientConn).Run()
      /go/tidb/server/conn.go:1079 +0x313
  github.com/pingcap/tidb/server.(*Server).onConn()
      /go/tidb/server/server.go:548 +0x14fc
  github.com/pingcap/tidb/server.(*Server).startNetworkListener·dwrap·35()
      /go/tidb/server/server.go:451 +0x47
Previous read at 0x00c0095f6840 by goroutine 132:
  github.com/pingcap/tidb/executor.(*ExecStmt).LogSlowQuery()
      /go/tidb/executor/adapter.go:942 +0x184
  github.com/pingcap/tidb/executor.(*ExecStmt).FinishExecuteStmt()
      /go/tidb/executor/adapter.go:897 +0x5cd
  github.com/pingcap/tidb/session.runStmt()
      /go/tidb/session/session.go:1717 +0x8c8
  github.com/pingcap/tidb/session.(*session).ExecuteStmt()
      /go/tidb/session/session.go:1582 +0xd93
  github.com/pingcap/tidb/session.(*session).ExecuteInternal()
      /go/tidb/session/session.go:1295 +0x4c4
  github.com/pingcap/tidb/ddl/util.RemoveFromGCDeleteRange()
      /go/tidb/ddl/util/util.go:117 +0x163
  github.com/pingcap/tidb/ddl/util.CompleteDeleteRange()
      /go/tidb/ddl/util/util.go:112 +0x1a9
  github.com/pingcap/tidb/ddl.(*delRange).doTask()
      /go/tidb/ddl/delete_range.go:233 +0x4d3
  github.com/pingcap/tidb/ddl.(*delRange).doDelRangeWork()
      /go/tidb/ddl/delete_range.go:186 +0x66e
  github.com/pingcap/tidb/ddl.(*delRange).startEmulator()
      /go/tidb/ddl/delete_range.go:150 +0x1c4
  github.com/pingcap/tidb/ddl.(*delRange).start·dwrap·31()
      /go/tidb/ddl/delete_range.go:126 +0x39 

1. Minimal reproduce step (Required)

make race

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

[hawkingrei]

/assign

[github-actions]

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