Issues #33565 and #56784 were caused by hangs in the child process
after fork, while it ran atfork handlers that ran into slow paths that
didn't work in the child.
CL 451735 worked around those two issues by calling a couple functions
at startup to try to warm up those child paths. That mostly worked,
but it broke programs using cgo with certain macOS frameworks (#57263).
CL 459175 reverted CL 451735.
This CL introduces a different fix: bypass the atfork child handlers
entirely. For a general fork call where the child and parent are both
meant to keep executing the original program, atfork handlers can be
necessary to fix any state that would otherwise be tied to the parent
process. But Go only uses fork as preparation for exec, and it takes
care to limit what it attempts to do in the child between the fork and
exec. In particular it doesn't use any of the things that the macOS
atfork handlers are trying to fix up (malloc, xpc, others). So we can
use the low-level fork system call (__fork) instead of the
atfork-wrapped one.
The full list of functions that can be called in a child after fork in
exec_libc2.go is:
- ptrace
- setsid
- setpgid
- getpid
- ioctl
- chroot
- setgroups
- setgid
- setuid
- chdir
- dup2
- fcntl
- close
- execve
- write
- exit
I disassembled all of these while attached to a hung exec.test binary
and confirmed that nearly all of them are making direct kernel calls,
not using anything that the atfork handler needs to fix up.
The exceptions are ioctl, fcntl, and exit.
The ioctl and fcntl implementations do some extra work around the
kernel call but don't call any other functions, so they should still
be OK. (If not, we could use __ioctl and __fcntl instead, but without
a good reason, we should keep using the standard entry points.)
The exit implementation calls atexit handlers. That is almost
certainly inappropriate in a failed fork child, so this CL changes
that call to __exit on darwin. To avoid making unnecessary changes at
this point in the release cycle, this CL leaves OpenBSD calling plain
exit, even though that is probably a bug in the OpenBSD port
(filed #57446).
Fixes#33565.
Fixes#56784.
Fixes#57263.
Fixes#56837.
Change-Id: I26812c26a72bdd7fcf72ec41899ba11cf6b9c4ab
Reviewed-on: https://go-review.googlesource.com/c/go/+/459176
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/459178
A future change to gofmt will rewrite
// Doc comment.
//go:foo
to
// Doc comment.
//
//go:foo
Apply that change preemptively to all comments (not necessarily just doc comments).
For #51082.
Change-Id: Iffe0285418d1e79d34526af3520b415a12203ca9
Reviewed-on: https://go-review.googlesource.com/c/go/+/384260
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Use dup3(oldfd, newfd, O_CLOEXEC) to atomically duplicate the file
descriptor and mark is as close-on-exec instead of dup2 & fcntl.
The dup3 system call first appeared in OpenBSD 5.7.
Change-Id: Ic06c2c7089dcdbd931ee24e5e8c316879d81474e
Reviewed-on: https://go-review.googlesource.com/c/go/+/389974
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
When these packages are released as part of Go 1.18,
Go 1.16 will no longer be supported, so we can remove
the +build tags in these files.
Ran go fix -fix=buildtag std cmd and then reverted the bootstrapDirs
as defined in src/cmd/dist/buildtool.go, which need to continue
to build with Go 1.4 for now.
Also reverted src/vendor and src/cmd/vendor, which will need
to be updated in their own repos first.
Manual changes in runtime/pprof/mprof_test.go to adjust line numbers.
For #41184.
Change-Id: Ic0f93f7091295b6abc76ed5cd6e6746e1280861e
Reviewed-on: https://go-review.googlesource.com/c/go/+/344955
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
These ioctls take a pid_t (generally a C integer aka int32) and not an int64 - we
currently get away with this on little endian 64 bit platforms, since the bytes
fall into the correct place, however this breaks on big endian 64 bit platforms
(like openbsd/mips64).
This is the same fix as CL 267605, however for libc based exec.
Updates #36435
Change-Id: I01ae4905cba5e1f8725fa6cb8c35403c511534b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/334881
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
openbsd/mips64 is now the only openbsd port that uses non-libc syscall - revise
build tags to reflect this.
Update #36435
Change-Id: I357b2dd2926d058e25e618fcca42c388587598a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/317919
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Convert the syscall package on openbsd/arm to use libc rather than performing
direct system calls.
Updates #36435
Change-Id: Iff3a91c959292cbf4e0a09c7fd34efc8e88ff83f
Reviewed-on: https://go-review.googlesource.com/c/go/+/315793
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Convert the syscall package on openbsd/386 to use libc rather than performing
direct system calls.
Updates #36435
Change-Id: Ifcfbca0e6b933762596a564243caa850dac01442
Reviewed-on: https://go-review.googlesource.com/c/go/+/287654
Trust: Joel Sing <joel@sing.id.au>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Fixes#37217
Change-Id: I0151bb77fc4c4552d1b19c31d784943b72f84b80
Reviewed-on: https://go-review.googlesource.com/c/go/+/313653
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
In CL 288092 we made Darwin syscall wrappers as ABIInternal, so
their addresses taken from Go using funcPC are the actual function
entries, not the wrappers.
As we introduced internal/abi.FuncPCABIxxx intrinsics, use that.
And change the assembly functions back to ABI0.
Do it on OpenBSD as well, as OpenBSD and Darwin share code
generator.
Change-Id: I408120795f7fc826637c867394248f8f373906bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/313230
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Make all our package sources use Go 1.17 gofmt format
(adding //go:build lines).
Part of //go:build change (#41184).
See https://golang.org/design/draft-gobuild
Change-Id: Ia0534360e4957e58cd9a18429c39d0e32a6addb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/294430
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Convert the syscall package on openbsd/arm64 to use libc rather than performing
direct system calls.
Updates #36435
Change-Id: I7e1da8537cea9ed9bf2676f181e56ae99383333f
Reviewed-on: https://go-review.googlesource.com/c/go/+/286815
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Convert the syscall package on openbsd/amd64 to use libc rather than performing
direct system calls.
Updates #36435
Change-Id: Ieb5926a91ed34f7c722e3667004ec484c86804ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/270380
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Russ Cox
Tobias Klauser
Joel Sing
Ian Lance Taylor
Cherry Zhang