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internal/poll: remove detection of buggy splice on old Linux versions

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The splice syscall is buggy prior to Linux 2.6.29. CL 113999 added a
workaround to detect buggy versions and disable use of splice for these.
As of Go 1.18 the minumum Linux version is 2.6.32. Thus, a non-buggy
implementation of the splice syscall can be assumed.

For #45964
Fixes #54505

Change-Id: Ied3a3334da7a3f7fa1280b7c5b1dfb9030219336
Reviewed-on: https://go-review.googlesource.com/c/go/+/422979
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
This commit is contained in:
Tobias Klauser 2022-08-17 22:21:23 +02:00 committed by Gopher Robot
parent b15c399a36
commit a2c2f06cad
1 changed files with 3 additions and 32 deletions
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35
src/internal/poll/splice_linux.go
View File

@ -5,10 +5,8 @@
package poll package poll
import ( import (
"internal/syscall/unix"
"runtime" "runtime"
"sync" "sync"
"sync/atomic"
"syscall" "syscall"
"unsafe" "unsafe"
) )
@ -207,40 +205,13 @@ func putPipe(p *splicePipe) {
splicePipePool.Put(p) splicePipePool.Put(p)
} }
var disableSplice unsafe.Pointer
// newPipe sets up a pipe for a splice operation. // newPipe sets up a pipe for a splice operation.
func newPipe() (sp *splicePipe) { func newPipe() *splicePipe {
p := (*bool)(atomic.LoadPointer(&disableSplice))
if p != nil && *p {
return nil
}
var fds [2]int var fds [2]int
// pipe2 was added in 2.6.27 and our minimum requirement is 2.6.23, so it if err := syscall.Pipe2(fds[:], syscall.O_CLOEXEC|syscall.O_NONBLOCK); err != nil {
// might not be implemented. Falling back to pipe is possible, but prior to
// 2.6.29 splice returns -EAGAIN instead of 0 when the connection is
// closed.
const flags = syscall.O_CLOEXEC | syscall.O_NONBLOCK
if err := syscall.Pipe2(fds[:], flags); err != nil {
return nil return nil
} }
return &splicePipe{splicePipeFields: splicePipeFields{rfd: fds[0], wfd: fds[1]}}
sp = &splicePipe{splicePipeFields: splicePipeFields{rfd: fds[0], wfd: fds[1]}}
if p == nil {
p = new(bool)
defer atomic.StorePointer(&disableSplice, unsafe.Pointer(p))
// F_GETPIPE_SZ was added in 2.6.35, which does not have the -EAGAIN bug.
if _, _, errno := syscall.Syscall(unix.FcntlSyscall, uintptr(fds[0]), syscall.F_GETPIPE_SZ, 0); errno != 0 {
*p = true
destroyPipe(sp)
return nil
}
}
return
} }
// destroyPipe destroys a pipe. // destroyPipe destroys a pipe.