diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala
index 807765c1e00a..48a5fb14707c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala
@@ -357,15 +357,19 @@ class CodegenContext {
 
   /**
    * It will count the lines of every Java function generated by whole-stage codegen,
-   * if there is a function of length greater than spark.sql.codegen.maxLinesPerFunction,
-   * it will return true.
+   * if there is a function of length greater than `maxLinesPerFunction`, it will return true.
+   * If `maxLinesPerFunction` has -1, it will always return false.
    */
   def isTooLongGeneratedFunction: Boolean = {
-    classFunctions.values.exists { _.values.exists {
-      code =>
-        val codeWithoutComments = CodeFormatter.stripExtraNewLinesAndComments(code)
-        codeWithoutComments.count(_ == '\n') > SQLConf.get.maxLinesPerFunction
+    val maxLinesPerFunc = SQLConf.get.maxLinesPerFunction
+    if (maxLinesPerFunc >= 0) {
+      classFunctions.values.exists { _.values.exists { code =>
+          val codeWithoutComments = CodeFormatter.stripExtraNewLinesAndComments(code)
+          codeWithoutComments.count(_ == '\n') > maxLinesPerFunc
+        }
       }
+    } else {
+      false
     }
   }
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
index a685099505ee..4c3ae81abe3f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
@@ -578,8 +578,10 @@ object SQLConf {
       "When the generated function exceeds this threshold, " +
       "the whole-stage codegen is deactivated for this subtree of the current query plan. " +
       "The default value 4000 is the max length of byte code JIT supported " +
-      "for a single function(8000) divided by 2.")
+      "for a single function(8000) divided by 2. Use -1 to disable this.")
     .intConf
+    .checkValue(maxLines => maxLines >= -1, "The maximum must not be a negative integer, " +
+      "except for -1 using to always activate whole-stage codegen")
     .createWithDefault(4000)
 
   val FILES_MAX_PARTITION_BYTES = buildConf("spark.sql.files.maxPartitionBytes")
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
index beeee6a97c8d..30ed836967b8 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
@@ -17,9 +17,7 @@
 
 package org.apache.spark.sql.execution
 
-import org.apache.spark.sql.{Column, Dataset, Row}
-import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
-import org.apache.spark.sql.catalyst.expressions.{Add, Literal, Stack}
+import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.expressions.codegen.CodegenContext
 import org.apache.spark.sql.execution.aggregate.HashAggregateExec
 import org.apache.spark.sql.execution.joins.BroadcastHashJoinExec
@@ -193,11 +191,15 @@ class WholeStageCodegenSuite extends SparkPlanTest with SharedSQLContext {
     }
   }
 
-  test("SPARK-21603 check there is not a too long generated function when threshold is Int.Max") {
+  test("SPARK-21603 check there is not a too long generated function when threshold is Max/-1") {
     withSQLConf(SQLConf.WHOLESTAGE_MAX_LINES_PER_FUNCTION.key -> Int.MaxValue.toString) {
       val ctx = genGroupByCodeGenContext(30)
       assert(ctx.isTooLongGeneratedFunction === false)
     }
+    withSQLConf(SQLConf.WHOLESTAGE_MAX_LINES_PER_FUNCTION.key -> "-1") {
+      val ctx = genGroupByCodeGenContext(30)
+      assert(ctx.isTooLongGeneratedFunction === false)
+    }
   }
 
   test("SPARK-21603 check there is a too long generated function when threshold is 0") {
@@ -206,4 +208,12 @@ class WholeStageCodegenSuite extends SparkPlanTest with SharedSQLContext {
       assert(ctx.isTooLongGeneratedFunction === true)
     }
   }
+
+  test("SPARK-21603 `maxLinesPerFunction` must not be negative") {
+    val errMsg = intercept[IllegalArgumentException] {
+      withSQLConf(SQLConf.WHOLESTAGE_MAX_LINES_PER_FUNCTION.key -> "-2") {}
+    }.getMessage
+    assert(errMsg.contains("The maximum must not be a negative integer, except for -1 using to " +
+      "always activate whole-stage codegen"))
+  }
 }