internal/syscall/unix: consolidate kernelVersion implementations

Currently, there are 3 functions returning Linux kernel version numbers.

Two of them are identical:
 - in net, initially added by commit 0a9dd47dd817904e;
 - in internal/poll, initially added by commit 1c7650aa93bd53;

(both were later fixed by commit 66c02645062561a).

The third one is a more complex, regexp-based implementation in
runtime/pprof, which is only used for a test.

Instead of adding one more, let's consolidate existing ones.

Remove the complex implementation, and move the simple one into
internal/syscall/unix. Use it from all the three places mentioned above.

Change-Id: I4a34d9ca47257743c16def30e4dd634e36056091
Reviewed-on: https://go-review.googlesource.com/c/go/+/424896
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

3 files changed, 3 insertions, 81 deletions

diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 28b8f4319e..31a4024be8 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"internal/abi"
 	"internal/profile"
+	"internal/syscall/unix"
 	"internal/testenv"
 	"io"
 	"math"
@@ -116,11 +117,8 @@ func TestCPUProfileMultithreadMagnitude(t *testing.T) {
 
 	// Linux [5.9,5.16) has a kernel bug that can break CPU timers on newly
 	// created threads, breaking our CPU accounting.
-	major, minor, patch, err := linuxKernelVersion()
-	if err != nil {
-		t.Errorf("Error determining kernel version: %v", err)
-	}
-	t.Logf("Running on Linux %d.%d.%d", major, minor, patch)
+	major, minor := unix.KernelVersion()
+	t.Logf("Running on Linux %d.%d", major, minor)
 	defer func() {
 		if t.Failed() {
 			t.Logf("Failure of this test may indicate that your system suffers from a known Linux kernel bug fixed on newer kernels. See https://golang.org/issue/49065.")
diff --git a/src/runtime/pprof/uname_linux_test.go b/src/runtime/pprof/uname_linux_test.go
deleted file mode 100644
index 8374c83f74..0000000000
--- a/src/runtime/pprof/uname_linux_test.go
+++ /dev/null
@@ -1,61 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build linux
-
-package pprof
-
-import (
-	"fmt"
-	"regexp"
-	"strconv"
-	"syscall"
-)
-
-var versionRe = regexp.MustCompile(`^(\d+)(?:\.(\d+)(?:\.(\d+))).*$`)
-
-func linuxKernelVersion() (major, minor, patch int, err error) {
-	var uname syscall.Utsname
-	if err := syscall.Uname(&uname); err != nil {
-		return 0, 0, 0, err
-	}
-
-	buf := make([]byte, 0, len(uname.Release))
-	for _, b := range uname.Release {
-		if b == 0 {
-			break
-		}
-		buf = append(buf, byte(b))
-	}
-	rl := string(buf)
-
-	m := versionRe.FindStringSubmatch(rl)
-	if m == nil {
-		return 0, 0, 0, fmt.Errorf("error matching version number in %q", rl)
-	}
-
-	v, err := strconv.ParseInt(m[1], 10, 64)
-	if err != nil {
-		return 0, 0, 0, fmt.Errorf("error parsing major version %q in %s: %w", m[1], rl, err)
-	}
-	major = int(v)
-
-	if len(m) >= 3 {
-		v, err := strconv.ParseInt(m[2], 10, 64)
-		if err != nil {
-			return 0, 0, 0, fmt.Errorf("error parsing minor version %q in %s: %w", m[2], rl, err)
-		}
-		minor = int(v)
-	}
-
-	if len(m) >= 4 {
-		v, err := strconv.ParseInt(m[3], 10, 64)
-		if err != nil {
-			return 0, 0, 0, fmt.Errorf("error parsing patch version %q in %s: %w", m[3], rl, err)
-		}
-		patch = int(v)
-	}
-
-	return
-}
diff --git a/src/runtime/pprof/uname_other_test.go b/src/runtime/pprof/uname_other_test.go
deleted file mode 100644
index 327640755b..0000000000
--- a/src/runtime/pprof/uname_other_test.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !linux
-
-package pprof
-
-import (
-	"errors"
-)
-
-func linuxKernelVersion() (major, minor, patch int, err error) {
-	return 0, 0, 0, errors.New("not running on linux")
-}