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ServerService used to own three mutexes coordinating six pieces of mutable state (exports, busy, controlState, controlSeq, controlSubs, LeaseManager). The lock-ordering rule that fixed the import/attach race in 0c892411a lived only as a comment. Two-mutex (fast/slow) ledger absorbs all of it; the two mutexes are never held simultaneously, so the ordering rule becomes a property of the type instead of a discipline callers must observe. TryReserveForImport closes the window where two concurrent OpReqImports could both pass the busy check before either marked busy.
77 lines
1.6 KiB
Go
77 lines
1.6 KiB
Go
//go:build linux || (darwin && cgo)
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package usbip
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import (
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"io"
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"net"
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"time"
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E "github.com/sagernet/sing/common/exceptions"
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)
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func (s *ServerService) acceptLoop(ln net.Listener) {
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for {
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conn, err := ln.Accept()
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if err != nil {
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select {
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case <-s.ctx.Done():
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return
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default:
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}
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if E.IsClosed(err) {
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return
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}
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//nolint:staticcheck // net.Error.Temporary predates net.ErrClosed; replacement needs a separate audit.
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if netError, isNetError := err.(net.Error); isNetError && netError.Temporary() {
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s.logger.Error("accept: ", err)
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if !sleepCtx(s.ctx, 200*time.Millisecond) {
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return
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}
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continue
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}
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s.logger.Error("accept: ", err)
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return
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}
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go s.dispatchConn(conn)
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}
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}
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func (s *ServerService) dispatchConn(conn net.Conn) {
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var prefix [controlPrefaceSize]byte
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if _, err := io.ReadFull(conn, prefix[:]); err != nil {
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s.logger.Debug("read connection preface: ", err)
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_ = conn.Close()
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return
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}
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if IsControlPreface(prefix[:]) {
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s.handleControlConn(conn)
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return
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}
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s.handleStandardConn(conn, ParseOpHeader(prefix[:]))
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}
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func (s *ServerService) readControlConn(sub *exportSubscriber, done chan<- struct{}) {
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defer close(done)
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var reader controlReader
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for {
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message, err := reader.read(sub.conn)
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if err != nil {
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return
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}
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frame := message.Frame
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switch frame.Type {
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case controlFramePing:
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s.ledger.HandleControlPing(sub)
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case controlFrameLeaseRequest:
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if supportsControlExtensions(sub.capabilities) {
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s.ledger.HandleControlLeaseRequest(s.ctx, sub, message.Payload)
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continue
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}
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return
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default:
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return
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}
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}
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}
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