internal/poll,syscall: drop the fallback for accept4 on linux/arm

For #67001

Change-Id: Ic0b91cd393046c53e41908e8dbbe2ab5fb6b8a74
Reviewed-on: https://go-review.googlesource.com/c/go/+/588216
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>

7 files changed, 7 insertions, 124 deletions

diff --git a/src/internal/poll/sock_cloexec.go b/src/internal/poll/sock_cloexec.go
index cbf7021804..466ee3139c 100644
--- a/src/internal/poll/sock_cloexec.go
+++ b/src/internal/poll/sock_cloexec.go
@@ -5,7 +5,7 @@
 // This file implements accept for platforms that provide a fast path for
 // setting SetNonblock and CloseOnExec.
 
-//go:build dragonfly || freebsd || (linux && !arm) || netbsd || openbsd
+//go:build dragonfly || freebsd || linux || netbsd || openbsd
 
 package poll
 
diff --git a/src/internal/poll/sock_cloexec_accept.go b/src/internal/poll/sock_cloexec_accept.go
deleted file mode 100644
index 4b86de59e0..0000000000
--- a/src/internal/poll/sock_cloexec_accept.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2013 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.
-
-// This file implements accept for platforms that provide a fast path for
-// setting SetNonblock and CloseOnExec, but don't necessarily have accept4.
-// This is the code we used for accept in Go 1.17 and earlier.
-// On Linux the accept4 system call was introduced in 2.6.28 kernel,
-// and our minimum requirement is 2.6.32, so we simplified the function.
-// Unfortunately, on ARM accept4 wasn't added until 2.6.36, so for ARM
-// only we continue using the older code.
-
-//go:build linux && arm
-
-package poll
-
-import "syscall"
-
-// Wrapper around the accept system call that marks the returned file
-// descriptor as nonblocking and close-on-exec.
-func accept(s int) (int, syscall.Sockaddr, string, error) {
-	ns, sa, err := Accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
-	switch err {
-	case nil:
-		return ns, sa, "", nil
-	default: // errors other than the ones listed
-		return -1, sa, "accept4", err
-	case syscall.ENOSYS: // syscall missing
-	case syscall.EINVAL: // some Linux use this instead of ENOSYS
-	case syscall.EACCES: // some Linux use this instead of ENOSYS
-	case syscall.EFAULT: // some Linux use this instead of ENOSYS
-	}
-
-	// See ../syscall/exec_unix.go for description of ForkLock.
-	// It is probably okay to hold the lock across syscall.Accept
-	// because we have put fd.sysfd into non-blocking mode.
-	// However, a call to the File method will put it back into
-	// blocking mode. We can't take that risk, so no use of ForkLock here.
-	ns, sa, err = AcceptFunc(s)
-	if err == nil {
-		syscall.CloseOnExec(ns)
-	}
-	if err != nil {
-		return -1, nil, "accept", err
-	}
-	if err = syscall.SetNonblock(ns, true); err != nil {
-		CloseFunc(ns)
-		return -1, nil, "setnonblock", err
-	}
-	return ns, sa, "", nil
-}
diff --git a/src/syscall/mkall.sh b/src/syscall/mkall.sh
index a3bc767628..b9a0ed3d4f 100755
--- a/src/syscall/mkall.sh
+++ b/src/syscall/mkall.sh
@@ -190,7 +190,7 @@ linux_amd64)
 	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
 	;;
 linux_arm)
-	GOOSARCH_in="syscall_linux_arm.go syscall_linux_accept.go"
+	GOOSARCH_in="syscall_linux_arm.go"
 	mkerrors="$mkerrors"
 	mksyscall="./mksyscall.pl -l32 -arm"
 	mksysnum="curl -s 'http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/arch/arm/include/uapi/asm/unistd.h' | ./mksysnum_linux.pl -"
diff --git a/src/syscall/syscall_linux.go b/src/syscall/syscall_linux.go
index 2706973596..032936398b 100644
--- a/src/syscall/syscall_linux.go
+++ b/src/syscall/syscall_linux.go
@@ -682,6 +682,10 @@ func anyToSockaddr(rsa *RawSockaddrAny) (Sockaddr, error) {
 	return nil, EAFNOSUPPORT
 }
 
+func Accept(fd int) (nfd int, sa Sockaddr, err error) {
+	return Accept4(fd, 0)
+}
+
 func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	var len _Socklen = SizeofSockaddrAny
diff --git a/src/syscall/syscall_linux_accept.go b/src/syscall/syscall_linux_accept.go
deleted file mode 100644
index 66c0f84cb8..0000000000
--- a/src/syscall/syscall_linux_accept.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// Copyright 2009 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.
-
-// We require Linux kernel version 2.6.32. The accept4 system call was
-// added in version 2.6.28, so in general we can use accept4.
-// Unfortunately, for ARM only, accept4 was added in version 2.6.36.
-// Handle that case here, by using a copy of the Accept function that
-// we used in Go 1.17.
-
-//go:build linux && arm
-
-package syscall
-
-//sys	accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error)
-
-func Accept(fd int) (nfd int, sa Sockaddr, err error) {
-	var rsa RawSockaddrAny
-	var len _Socklen = SizeofSockaddrAny
-	// Try accept4 first for Android and newer kernels.
-	nfd, err = accept4(fd, &rsa, &len, 0)
-	if err == ENOSYS {
-		nfd, err = accept(fd, &rsa, &len)
-	}
-	if err != nil {
-		return
-	}
-	sa, err = anyToSockaddr(&rsa)
-	if err != nil {
-		Close(nfd)
-		nfd = 0
-	}
-	return
-}
diff --git a/src/syscall/syscall_linux_accept4.go b/src/syscall/syscall_linux_accept4.go
deleted file mode 100644
index 74898672c0..0000000000
--- a/src/syscall/syscall_linux_accept4.go
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2009 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.
-
-// This file provides the Accept function used on all systems
-// other than arm. See syscall_linux_accept.go for why.
-
-//go:build linux && !arm
-
-package syscall
-
-func Accept(fd int) (nfd int, sa Sockaddr, err error) {
-	var rsa RawSockaddrAny
-	var len _Socklen = SizeofSockaddrAny
-	nfd, err = accept4(fd, &rsa, &len, 0)
-	if err != nil {
-		return
-	}
-	sa, err = anyToSockaddr(&rsa)
-	if err != nil {
-		Close(nfd)
-		nfd = 0
-	}
-	return
-}
diff --git a/src/syscall/zsyscall_linux_arm.go b/src/syscall/zsyscall_linux_arm.go
index a386120f78..2929a3bda5 100644
--- a/src/syscall/zsyscall_linux_arm.go
+++ b/src/syscall/zsyscall_linux_arm.go
@@ -1,4 +1,4 @@
-// mksyscall.pl -l32 -arm -tags linux,arm syscall_linux.go syscall_linux_arm.go syscall_linux_accept.go
+// mksyscall.pl -l32 -arm -tags linux,arm syscall_linux.go syscall_linux_arm.go
 // Code generated by the command above; DO NOT EDIT.
 
 //go:build linux && arm
@@ -1615,14 +1615,3 @@ func setrlimit1(resource int, rlim *rlimit32) (err error) {
 	}
 	return
 }
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
-func accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error) {
-	r0, _, e1 := Syscall(SYS_ACCEPT, uintptr(s), uintptr(unsafe.Pointer(rsa)), uintptr(unsafe.Pointer(addrlen)))
-	fd = int(r0)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}