net/{batching,udprelay},wgengine/magicsock: add SO_RXQ_OVFL clientmetrics
For the purpose of improved observability of UDP socket receive buffer overflows on Linux. Updates tailscale/corp#37679 Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit is contained in:
Jordan Whited
committed by
Jordan Whited
Jordan Whited
parent
660a4608d2
commit
96dde53b43
+180
-25
@@ -5,10 +5,13 @@ package batching
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import (
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"encoding/binary"
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"io"
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"math"
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"net"
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"testing"
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"unsafe"
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qt "github.com/frankban/quicktest"
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"github.com/tailscale/wireguard-go/conn"
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"golang.org/x/net/ipv6"
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"golang.org/x/sys/unix"
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@@ -317,35 +320,187 @@ func TestMinReadBatchMsgsLen(t *testing.T) {
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}
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}
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func Test_getGSOSizeFromControl_MultipleMessages(t *testing.T) {
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// Test that getGSOSizeFromControl correctly parses UDP_GRO when it's not the first control message.
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const expectedGSOSize = 1420
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func makeControlMsg(cmsgLevel, cmsgType int32, dataLen int) []byte {
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msgLen := unix.CmsgSpace(dataLen)
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msg := make([]byte, msgLen)
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hdr2 := (*unix.Cmsghdr)(unsafe.Pointer(&msg[0]))
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hdr2.Level = cmsgLevel
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hdr2.Type = cmsgType
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hdr2.SetLen(unix.CmsgLen(dataLen))
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return msg
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}
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// First message: IP_TOS
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firstMsgLen := unix.CmsgSpace(1)
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firstMsg := make([]byte, firstMsgLen)
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hdr1 := (*unix.Cmsghdr)(unsafe.Pointer(&firstMsg[0]))
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hdr1.Level = unix.SOL_IP
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hdr1.Type = unix.IP_TOS
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hdr1.SetLen(unix.CmsgLen(1))
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firstMsg[unix.SizeofCmsghdr] = 0
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func gsoControl(gso uint16) []byte {
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msg := makeControlMsg(unix.SOL_UDP, unix.UDP_GRO, 2)
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binary.NativeEndian.PutUint16(msg[unix.SizeofCmsghdr:], gso)
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return msg
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}
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// Second message: UDP_GRO
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secondMsgLen := unix.CmsgSpace(2)
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secondMsg := make([]byte, secondMsgLen)
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hdr2 := (*unix.Cmsghdr)(unsafe.Pointer(&secondMsg[0]))
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hdr2.Level = unix.SOL_UDP
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hdr2.Type = unix.UDP_GRO
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hdr2.SetLen(unix.CmsgLen(2))
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binary.NativeEndian.PutUint16(secondMsg[unix.SizeofCmsghdr:], expectedGSOSize)
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func rxqOverflowsControl(count uint32) []byte {
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msg := makeControlMsg(unix.SOL_SOCKET, unix.SO_RXQ_OVFL, 4)
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binary.NativeEndian.PutUint32(msg[unix.SizeofCmsghdr:], count)
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return msg
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}
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control := append(firstMsg, secondMsg...)
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func Test_getRXQOverflowsMetric(t *testing.T) {
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c := qt.New(t)
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m := getRXQOverflowsMetric("")
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c.Assert(m, qt.IsNil)
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m = getRXQOverflowsMetric("rxq_overflows")
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c.Assert(m, qt.IsNotNil)
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wantM := getRXQOverflowsMetric("rxq_overflows")
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c.Assert(m, qt.Equals, wantM)
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uniq := getRXQOverflowsMetric("rxq_overflows_uniq")
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c.Assert(m, qt.Not(qt.Equals), uniq)
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}
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gsoSize, err := getGSOSizeFromControl(control)
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if err != nil {
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t.Fatalf("unexpected error: %v", err)
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func Test_getRXQOverflowsFromControl(t *testing.T) {
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malformedControlMsg := gsoControl(1)
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hdr := (*unix.Cmsghdr)(unsafe.Pointer(&malformedControlMsg[0]))
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hdr.SetLen(1)
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tests := []struct {
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name string
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control []byte
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want uint32
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wantErr bool
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}{
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{
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name: "malformed",
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control: malformedControlMsg,
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want: 0,
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wantErr: true,
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},
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{
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name: "gso",
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control: gsoControl(1),
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want: 0,
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wantErr: false,
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},
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{
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name: "rxq overflows",
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control: rxqOverflowsControl(1),
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want: 1,
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wantErr: false,
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},
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{
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name: "multiple cmsg rxq overflows at head",
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control: append(rxqOverflowsControl(1), gsoControl(1)...),
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want: 1,
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wantErr: false,
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},
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{
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name: "multiple cmsg rxq overflows at tail",
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control: append(gsoControl(1), rxqOverflowsControl(1)...),
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want: 1,
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wantErr: false,
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},
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}
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if gsoSize != expectedGSOSize {
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t.Errorf("got GSO size %d, want %d", gsoSize, expectedGSOSize)
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got, err := getRXQOverflowsFromControl(tt.control)
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if (err != nil) != tt.wantErr {
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t.Errorf("getRXQOverflowsFromControl() error = %v, wantErr %v", err, tt.wantErr)
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return
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}
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if got != tt.want {
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t.Errorf("getRXQOverflowsFromControl() got = %v, want %v", got, tt.want)
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}
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})
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}
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}
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func Test_getGSOSizeFromControl(t *testing.T) {
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malformedControlMsg := gsoControl(1)
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hdr := (*unix.Cmsghdr)(unsafe.Pointer(&malformedControlMsg[0]))
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hdr.SetLen(1)
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tests := []struct {
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name string
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control []byte
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want int
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wantErr bool
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}{
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{
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name: "malformed",
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control: malformedControlMsg,
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want: 0,
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wantErr: true,
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},
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{
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name: "gso",
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control: gsoControl(1),
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want: 1,
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wantErr: false,
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},
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{
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name: "rxq overflows",
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control: rxqOverflowsControl(1),
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want: 0,
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wantErr: false,
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},
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{
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name: "multiple cmsg gso at tail",
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control: append(rxqOverflowsControl(1), gsoControl(1)...),
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want: 1,
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wantErr: false,
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},
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{
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name: "multiple cmsg gso at head",
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control: append(gsoControl(1), rxqOverflowsControl(1)...),
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want: 1,
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wantErr: false,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got, err := getGSOSizeFromControl(tt.control)
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if (err != nil) != tt.wantErr {
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t.Errorf("getGSOSizeFromControl() error = %v, wantErr %v", err, tt.wantErr)
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return
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}
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if got != tt.want {
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t.Errorf("getGSOSizeFromControl() got = %v, want %v", got, tt.want)
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}
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})
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}
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}
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func Test_linuxBatchingConn_handleRXQOverflowCounter(t *testing.T) {
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c := qt.New(t)
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conn := &linuxBatchingConn{
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rxqOverflowsMetric: getRXQOverflowsMetric("test_handleRXQOverflowCounter"),
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}
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conn.rxqOverflowsMetric.Set(0) // test count > 1 will accumulate, reset
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// n == 0
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conn.handleRXQOverflowCounter([]ipv6.Message{{}}, 0, nil)
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c.Assert(conn.rxqOverflowsMetric.Value(), qt.Equals, int64(0))
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// rxErr non-nil
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conn.handleRXQOverflowCounter([]ipv6.Message{{}}, 0, io.EOF)
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c.Assert(conn.rxqOverflowsMetric.Value(), qt.Equals, int64(0))
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// nonzero counter
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control := rxqOverflowsControl(1)
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conn.handleRXQOverflowCounter([]ipv6.Message{{
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OOB: control,
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NN: len(control),
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}}, 1, nil)
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c.Assert(conn.rxqOverflowsMetric.Value(), qt.Equals, int64(1))
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// nonzero counter, no change
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conn.handleRXQOverflowCounter([]ipv6.Message{{
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OOB: control,
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NN: len(control),
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}}, 1, nil)
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c.Assert(conn.rxqOverflowsMetric.Value(), qt.Equals, int64(1))
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// counter rollover
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control = rxqOverflowsControl(0)
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conn.handleRXQOverflowCounter([]ipv6.Message{{
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OOB: control,
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NN: len(control),
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}}, 1, nil)
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c.Assert(conn.rxqOverflowsMetric.Value(), qt.Equals, int64(1+math.MaxUint32))
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}
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