internal/poll:add SPLICE_F_NONBLOCK flag for splice to avoid insonsistency with O_NONBLOC

internal/poll:add SPLICE_F_NONBLOCK flag for splice to avoid insonsistency with O_NONBLOC

Signed-off-by: EulerOSWander <314264452@qq.com>
(cherry picked from commit 1e4bf241308377399305e37d1993066ca37baaa7)

backport-0016-release-branch.go1.21-internal-poll-add-SPLICE_F_NON.patch

@@ -0,0 +1,79 @@
+From fef8644451930464ffd9f13c82bcd451f58fa575 Mon Sep 17 00:00:00 2001
+From: Andy Pan <panjf2000@gmail.com>
+Date: Tue, 17 Oct 2023 22:38:17 +0800
+Subject: [PATCH 03/20] [release-branch.go1.21] internal/poll: add
+ SPLICE_F_NONBLOCK flag for splice to avoid inconsistency with O_NONBLOCK
+
+Fixes #63801
+Updates #59041
+Updates #63795
+
+Conflict:NA
+Reference:https://go-review.googlesource.com/c/go/+/536015
+
+Details: https://github.com/golang/go/issues/59041#issuecomment-1766610087
+
+Change-Id: Id3fc1df6d86b7c4cc383d09f9465fa8f4cc2a559
+Reviewed-on: https://go-review.googlesource.com/c/go/+/536015
+Reviewed-by: Bryan Mills <bcmills@google.com>
+Reviewed-by: Ian Lance Taylor <iant@google.com>
+LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
+Auto-Submit: Ian Lance Taylor <iant@google.com>
+(cherry picked from commit 40cdf69fc9279ab28f84a6e0f965de8382c578fe)
+Reviewed-on: https://go-review.googlesource.com/c/go/+/538117
+Auto-Submit: Heschi Kreinick <heschi@google.com>
+Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
+Reviewed-by: Heschi Kreinick <heschi@google.com>
+---
+ src/internal/poll/splice_linux.go | 21 +++++++++++++++++++--
+ 1 file changed, 19 insertions(+), 2 deletions(-)
+
+diff --git a/src/internal/poll/splice_linux.go b/src/internal/poll/splice_linux.go
+index 9505c5dcfc1e..72cca34fe4ae 100644
+--- a/src/internal/poll/splice_linux.go
++++ b/src/internal/poll/splice_linux.go
+@@ -13,6 +13,12 @@ import (
+ )
+ 
+ const (
++	// spliceNonblock doesn't make the splice itself necessarily nonblocking
++	// (because the actual file descriptors that are spliced from/to may block
++	// unless they have the O_NONBLOCK flag set), but it makes the splice pipe
++	// operations nonblocking.
++	spliceNonblock = 0x2
++
+ 	// maxSpliceSize is the maximum amount of data Splice asks
+ 	// the kernel to move in a single call to splice(2).
+ 	// We use 1MB as Splice writes data through a pipe, and 1MB is the default maximum pipe buffer size,
+@@ -89,7 +95,11 @@ func spliceDrain(pipefd int, sock *FD, max int) (int, error) {
+ 		return 0, err
+ 	}
+ 	for {
+-		n, err := splice(pipefd, sock.Sysfd, max, 0)
++		// In theory calling splice(2) with SPLICE_F_NONBLOCK could end up an infinite loop here,
++		// because it could return EAGAIN ceaselessly when the write end of the pipe is full,
++		// but this shouldn't be a concern here, since the pipe buffer must be sufficient for
++		// this data transmission on the basis of the workflow in Splice.
++		n, err := splice(pipefd, sock.Sysfd, max, spliceNonblock)
+ 		if err == syscall.EINTR {
+ 			continue
+ 		}
+@@ -127,7 +137,14 @@ func splicePump(sock *FD, pipefd int, inPipe int) (int, error) {
+ 	}
+ 	written := 0
+ 	for inPipe > 0 {
+-		n, err := splice(sock.Sysfd, pipefd, inPipe, 0)
++		// In theory calling splice(2) with SPLICE_F_NONBLOCK could end up an infinite loop here,
++		// because it could return EAGAIN ceaselessly when the read end of the pipe is empty,
++		// but this shouldn't be a concern here, since the pipe buffer must contain inPipe size of
++		// data on the basis of the workflow in Splice.
++		n, err := splice(sock.Sysfd, pipefd, inPipe, spliceNonblock)
++		if err == syscall.EINTR {
++			continue
++		}
+ 		// Here, the condition n == 0 && err == nil should never be
+ 		// observed, since Splice controls the write side of the pipe.
+ 		if n > 0 {
+-- 
+2.33.0
+

golang.spec

@@ -66,7 +66,7 @@
 
 Name:           golang
 Version:        1.21.4
-Release:        17
+Release:        18
 Summary:        The Go Programming Language
 License:        BSD and Public Domain
 URL:            https://golang.org/
@@ -136,6 +136,7 @@ Patch6012:	backport-0012-net-http-send-body-or-close-connection-on-expect-100.pa
 Patch6013:	backport-0013-release-branch.go1.21-net-http-update-bundled-golang.patch
 Patch6014:	backport-0014-cmd-compile-handle-constant-pointer-offsets-in-dead-.patch
 Patch6015:	backport-0015-release-branch.go1.21-cmd-compile-ensure-pointer-ari.patch
+Patch6016:	backport-0016-release-branch.go1.21-internal-poll-add-SPLICE_F_NON.patch
 
 ExclusiveArch:  %{golang_arches}
 
@@ -374,6 +375,9 @@ fi
 %files devel -f go-tests.list -f go-misc.list -f go-src.list
 
 %changelog
+* Thu Aug 1 2024 EulerOSWander <314264452@qq.com> - 1.21.4-18
+- internal/poll:add SPLICE_F_NONBLOCK flag for splice to avoid insonsistency with O_NONBLOCK
+
 * Mon Jul 30 2024 jingxiaolu <lujingxiao@huawei.com> - 1.21.4-17
 - cmd/compile: ensure pointer arithmetic happens after the nil check