152 lines
3.9 KiB
Diff
152 lines
3.9 KiB
Diff
From ab4bfbf2bea972772e5e879f0da6e9e8de407e35 Mon Sep 17 00:00:00 2001
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From: Ian Lance Taylor <iant@golang.org>
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Date: Fri, 29 Mar 2024 11:41:57 +0800
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Subject: [PATCH 1/2] [1.17 backport]runtime: decrement netpollWaiters in
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netpollunblock
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We used to decrement it in netpollgoready, but that missed
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the common case of a descriptor becoming ready due to I/O.
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All calls to netpollgoready go through netpollunblock,
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so this shouldn't miss any decrements we missed before.
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Note:
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The upstream does not submit this change to go1.17 according to
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the rules of MinorReleases.
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Edited-by: wangshuo
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Fixes #60782
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Change-Id: Ideefefa1ac96ca38e09fe2dd5d595c5dd7883237
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Reviewed-on: https://go-review.googlesource.com/c/go/+/503923
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TryBot-Result: Gopher Robot <gobot@golang.org>
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Reviewed-by: Ian Lance Taylor <iant@google.com>
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Run-TryBot: Ian Lance Taylor <iant@golang.org>
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Run-TryBot: Ian Lance Taylor <iant@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
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Auto-Submit: Ian Lance Taylor <iant@google.com>
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Signed-off-by: Wang Shuo <wangshuo@kylinos.cn>
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---
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src/runtime/crash_test.go | 9 +++
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src/runtime/netpoll.go | 4 +-
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src/runtime/testdata/testprognet/waiters.go | 69 +++++++++++++++++++++
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3 files changed, 81 insertions(+), 1 deletion(-)
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create mode 100644 src/runtime/testdata/testprognet/waiters.go
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diff --git a/src/runtime/crash_test.go b/src/runtime/crash_test.go
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index e0c0bac..800686b 100644
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--- a/src/runtime/crash_test.go
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+++ b/src/runtime/crash_test.go
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@@ -807,3 +807,12 @@ func TestDoublePanic(t *testing.T) {
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}
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}
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}
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+
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+func TestNetpollWaiters(t *testing.T) {
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+ t.Parallel()
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+ output := runTestProg(t, "testprognet", "NetpollWaiters")
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+ want := "OK\n"
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+ if output != want {
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+ t.Fatalf("output is not %q\n%s", want, output)
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+ }
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+}
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diff --git a/src/runtime/netpoll.go b/src/runtime/netpoll.go
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index 4f8d244..7175c7f 100644
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--- a/src/runtime/netpoll.go
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+++ b/src/runtime/netpoll.go
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@@ -477,13 +477,15 @@ func netpollunblock(pd *pollDesc, mode int32, ioready bool) *g {
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// will check for timeout/cancel before waiting.
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return nil
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}
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- var new uintptr
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+ new := pdNil
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if ioready {
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new = pdReady
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}
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if atomic.Casuintptr(gpp, old, new) {
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if old == pdWait {
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old = 0
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+ } else if old != 0 {
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+ netpollWaiters.Add(-1)
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}
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return (*g)(unsafe.Pointer(old))
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}
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diff --git a/src/runtime/testdata/testprognet/waiters.go b/src/runtime/testdata/testprognet/waiters.go
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new file mode 100644
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index 0000000..480e872
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--- /dev/null
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+++ b/src/runtime/testdata/testprognet/waiters.go
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@@ -0,0 +1,69 @@
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+// Copyright 2023 The Go Authors. All rights reserved.
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+// Use of this source code is governed by a BSD-style
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+// license that can be found in the LICENSE file.
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+
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+package main
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+
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+import (
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+ "fmt"
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+ "io"
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+ "log"
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+ "net"
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+ "runtime/internal/atomic"
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+ "sync"
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+ "time"
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+ _ "unsafe" // for go:linkname
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+)
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+
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+// The bug is that netpollWaiters increases monotonically.
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+// This doesn't cause a problem until it overflows.
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+// Use linkname to see the value.
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+//go:linkname netpollWaiters runtime.netpollWaiters
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+var netpollWaiters uint32
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+
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+func init() {
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+ register("NetpollWaiters", NetpollWaiters)
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+}
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+
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+func NetpollWaiters() {
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+ listener, err := net.Listen("tcp", "127.0.0.1:0")
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+ if err != nil {
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+ log.Fatal(err)
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+ }
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+
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+ var wg sync.WaitGroup
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+ wg.Add(1)
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+ go func() {
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+ defer wg.Done()
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+ conn, err := listener.Accept()
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+ if err != nil {
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+ log.Fatal(err)
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+ }
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+ defer conn.Close()
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+ if _, err := io.Copy(io.Discard, conn); err != nil {
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+ log.Fatal(err)
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+ }
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+ }()
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+
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+ wg.Add(1)
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+ go func() {
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+ defer wg.Done()
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+ conn, err := net.Dial("tcp", listener.Addr().String())
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+ if err != nil {
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+ log.Fatal(err)
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+ }
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+ defer conn.Close()
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+ for i := 0; i < 10; i++ {
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+ fmt.Fprintf(conn, "%d\n", i)
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+ time.Sleep(time.Millisecond)
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+ }
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+ }()
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+
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+ wg.Wait()
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+ if v := atomic.Load(&netpollWaiters); v != 0 {
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+ log.Fatalf("current waiters %v", v)
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+ }
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+
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+ fmt.Println("OK")
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+}
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+
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--
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2.27.0
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