wgengine: avoid the need to reenter the engine lock on double close

Updates #8059

Signed-off-by: James Tucker <james@tailscale.com>
This commit is contained in:
James Tucker 2023-05-04 15:51:44 -07:00
parent d1ce7a9b5e
commit f275107206
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@ -15,6 +15,7 @@
"runtime"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/tailscale/wireguard-go/device"
@ -125,10 +126,10 @@ type userspaceEngine struct {
destIPActivityFuncs map[netip.Addr]func()
statusBufioReader *bufio.Reader // reusable for UAPI
lastStatusPollTime mono.Time // last time we polled the engine status
closing atomic.Bool // Close was called (even if we're still closing)
mu sync.Mutex // guards following; see lock order comment below
netMap *netmap.NetworkMap // or nil
closing bool // Close was called (even if we're still closing)
statusCallback StatusCallback
peerSequence []key.NodePublic
endpoints []tailcfg.Endpoint
@ -1022,8 +1023,8 @@ func (e *userspaceEngine) getStatus() (*Status, error) {
// (See comment in userspaceEngine's declaration.)
derpConns := e.magicConn.DERPs()
closing := e.closing.Load()
e.mu.Lock()
closing := e.closing
peerKeys := make([]key.NodePublic, len(e.peerSequence))
copy(peerKeys, e.peerSequence)
localAddrs := append([]tailcfg.Endpoint(nil), e.endpoints...)
@ -1083,13 +1084,9 @@ func (e *userspaceEngine) RequestStatus() {
}
func (e *userspaceEngine) Close() {
e.mu.Lock()
if e.closing {
e.mu.Unlock()
if e.closing.Swap(true) {
return
}
e.closing = true
e.mu.Unlock()
r := bufio.NewReader(strings.NewReader(""))
e.wgdev.IpcSetOperation(r)