Lock checksum calculation for v1 CPUManager state to pre 1.18 logic

The updated CPUManager from PR #84462 implements logic to migrate the
CPUManager checkpoint file from an old format to a new one. To do so, it
defines the following types:

```
type CPUManagerCheckpoint = CPUManagerCheckpointV2
type CPUManagerCheckpointV1 struct {  ...  }
type CPUManagerCheckpointV2 struct {  ...  }
```

This replaces the old definition of just:

```
type CPUManagerCheckpoint struct {  ...  }
```

Code was put in place to ensure proper migration from checkpoints in V1
format to checkpoints in V2 format. However (and this is a big however),
all of the unit tests were performed on V1 checkpoints that were
generated using the type name `CPUManagerCheckpointV1` and not the
original type name of `CPUManagerCheckpoint`. As such, the checksum in
the checkpoint file uses the `CPUManagerCheckpointV1` type to calculate
its checksum and not the original type name of `CPUManagerCheckpoint`.

This causes problems in the real world since all pre-1.18 checkpoint
files will have been generated with the original type name of
`CPUManagerCheckpoint`. When verifying the checksum of the checkpoint
file across an upgrade to 1.18, the checksum is calculated assuming
a type name of `CPUManagerCheckpointV1` (which is incorrect) and the
file is seen to be corrupt.

This patch ensures that all V1 checksums are verified against a type
name of `CPUManagerCheckpoint` instead of ``CPUManagerCheckpointV1`.
It also locks the algorithm used to calculate the checksum in place,
since it wil never change in the future (for pre-1.18 checkpoint
files at least).

pkg/kubelet/cm/cpumanager/state/BUILD

@@ -17,6 +17,7 @@ go_library(
         "//pkg/kubelet/checkpointmanager/errors:go_default_library",
         "//pkg/kubelet/cm/cpumanager/containermap:go_default_library",
         "//pkg/kubelet/cm/cpuset:go_default_library",
+        "//vendor/github.com/davecgh/go-spew/spew:go_default_library",
         "//vendor/k8s.io/klog:go_default_library",
     ],
 )

pkg/kubelet/cm/cpumanager/state/checkpoint.go

@@ -18,9 +18,14 @@ package state
 
 import (
 	"encoding/json"
+	"hash/fnv"
+	"strings"
+
+	"github.com/davecgh/go-spew/spew"
 
 	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager"
 	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum"
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors"
 )
 
 // CPUManagerCheckpoint struct is used to store cpu/pod assignments in a checkpoint
@@ -95,11 +100,27 @@ func (cp *CPUManagerCheckpointV1) VerifyChecksum() error {
 		// accept empty checksum for compatibility with old file backend
 		return nil
 	}
+
+	printer := spew.ConfigState{
+		Indent:         " ",
+		SortKeys:       true,
+		DisableMethods: true,
+		SpewKeys:       true,
+	}
+
 	ck := cp.Checksum
 	cp.Checksum = 0
-	err := ck.Verify(cp)
+	object := printer.Sprintf("%#v", cp)
+	object = strings.Replace(object, "CPUManagerCheckpointV1", "CPUManagerCheckpoint", 1)
 	cp.Checksum = ck
-	return err
+
+	hash := fnv.New32a()
+	printer.Fprintf(hash, "%v", object)
+	if cp.Checksum != checksum.Checksum(hash.Sum32()) {
+		return errors.ErrCorruptCheckpoint
+	}
+
+	return nil
 }
 
 // VerifyChecksum verifies that current checksum of checkpoint is valid in v2 format

pkg/kubelet/cm/cpumanager/state/state_checkpoint_test.go

@@ -154,6 +154,20 @@ func TestCheckpointStateRestore(t *testing.T) {
 			`could not parse cpuset "asd" for container "container2" in pod "pod": strconv.Atoi: parsing "asd": invalid syntax`,
 			&stateMemory{},
 		},
+		{
+			"Restore checkpoint from checkpoint with v1 checksum",
+			`{
+				"policyName": "none",
+				"defaultCPUSet": "1-3",
+				"checksum": 1694838852
+			}`,
+			"none",
+			containermap.ContainerMap{},
+			"",
+			&stateMemory{
+				defaultCPUSet: cpuset.NewCPUSet(1, 2, 3),
+			},
+		},
 		{
 			"Restore checkpoint with migration",
 			`{
@@ -163,7 +177,7 @@ func TestCheckpointStateRestore(t *testing.T) {
 					"containerID1": "4-6",
 					"containerID2": "1-3"
 				},
-				"checksum": 2832947348
+				"checksum": 3680390589
 			}`,
 			"none",
 			func() containermap.ContainerMap {