From 0a9dd47dd817904ec2b4a80b551e6050218ee8a6 Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong@orijtech.com>
Date: Tue, 22 Sep 2020 09:30:31 +0700
Subject: net: reflect TCP backlog size update of uint16->uint32 on Linux

The sk_max_ack_backlog was increased from uint16 to uint32 in kernel
version 4.1 and above, so adopt that change to maxListenerBacklog.

See https://github.com/torvalds/linux/commit/becb74f0acca19b5abfcb24dc602530f3deea66a

Fixes #41470

Change-Id: I63a142eb28f3ac3acaca57f0903c085c6cb15a6e
Reviewed-on: https://go-review.googlesource.com/c/go/+/255898
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
---
 src/net/sock_linux.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 58 insertions(+), 4 deletions(-)

(limited to 'src/net/sock_linux.go')

diff --git a/src/net/sock_linux.go b/src/net/sock_linux.go
index 7bca37605e..4d91001937 100644
--- a/src/net/sock_linux.go
+++ b/src/net/sock_linux.go
@@ -6,6 +6,62 @@ package net
 
 import "syscall"
 
+func kernelVersion() (major int, minor int) {
+	var uname syscall.Utsname
+	if err := syscall.Uname(&uname); err != nil {
+		return
+	}
+
+	rl := uname.Release
+	var values [2]int
+	vi := 0
+	value := 0
+	for _, c := range rl {
+		if c >= '0' && c <= '9' {
+			value = (value * 10) + int(c-'0')
+		} else {
+			// Note that we're assuming N.N.N here.  If we see anything else we are likely to
+			// mis-parse it.
+			values[vi] = value
+			vi++
+			if vi >= len(values) {
+				break
+			}
+		}
+	}
+	switch vi {
+	case 0:
+		return 0, 0
+	case 1:
+		return values[0], 0
+	case 2:
+		return values[0], values[1]
+	}
+	return
+}
+
+// Linux stores the backlog as:
+//
+//  - uint16 in kernel version < 4.1,
+//  - uint32 in kernel version >= 4.1
+//
+// Truncate number to avoid wrapping.
+//
+// See issue 5030 and 41470.
+func maxAckBacklog(n int) int {
+	major, minor := kernelVersion()
+	size := 16
+	if major > 4 || (major == 4 && minor >= 1) {
+		size = 32
+	}
+
+	var max uint = 1<<size - 1
+	if uint(n) > max {
+		n = int(max)
+	}
+	return n
+}
+
 func maxListenerBacklog() int {
 	fd, err := open("/proc/sys/net/core/somaxconn")
 	if err != nil {
@@ -21,11 +77,9 @@ func maxListenerBacklog() int {
 	if n == 0 || !ok {
 		return syscall.SOMAXCONN
 	}
-	// Linux stores the backlog in a uint16.
-	// Truncate number to avoid wrapping.
-	// See issue 5030.
+
 	if n > 1<<16-1 {
-		n = 1<<16 - 1
+		return maxAckBacklog(n)
 	}
 	return n
 }
-- 
cgit v1.3


From 66c02645062561ac29d00297e8d8c49698b2e4da Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Thu, 19 Nov 2020 19:15:57 -0800
Subject: net, internal/poll: reset value before adding in minor kernel version

Fixes #42733

Change-Id: I5446aeb5de13cd70212755fb12c9bc484f343c74
Reviewed-on: https://go-review.googlesource.com/c/go/+/271846
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
---
 src/internal/poll/copy_file_range_linux.go | 1 +
 src/net/sock_linux.go                      | 1 +
 2 files changed, 2 insertions(+)

(limited to 'src/net/sock_linux.go')

diff --git a/src/internal/poll/copy_file_range_linux.go b/src/internal/poll/copy_file_range_linux.go
index 1635bb1bfc..fc34aef4cb 100644
--- a/src/internal/poll/copy_file_range_linux.go
+++ b/src/internal/poll/copy_file_range_linux.go
@@ -35,6 +35,7 @@ func kernelVersion() (major int, minor int) {
 			if vi >= len(values) {
 				break
 			}
+			value = 0
 		}
 	}
 	switch vi {
diff --git a/src/net/sock_linux.go b/src/net/sock_linux.go
index 4d91001937..9f62ed3dee 100644
--- a/src/net/sock_linux.go
+++ b/src/net/sock_linux.go
@@ -27,6 +27,7 @@ func kernelVersion() (major int, minor int) {
 			if vi >= len(values) {
 				break
 			}
+			value = 0
 		}
 	}
 	switch vi {
-- 
cgit v1.3