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sync/atomic: compare and swap of inconsistently typed values with uninitialized Value #52612

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wwade opened this issue Apr 28, 2022 · 4 comments
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sync/atomic: compare and swap of inconsistently typed values with uninitialized Value #52612

wwade opened this issue Apr 28, 2022 · 4 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. release-blocker
Milestone
Go1.19

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@wwade
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wwade commented Apr 28, 2022

What version of Go are you using (go version)?

$ go version
go version go1.18.1 linux/amd64

Does this issue reproduce with the latest release?

Yes. 1.18 and tip on play. Not in 1.17.9. Also docker run golang:1.18.1 .

This does appear to be a regression from 3a0cd11. In CompareAndSwap it's not checking against firstStoreInProgress.

What operating system and processor architecture are you using (go env)?

go env Output
$ docker run --rm -it -v $PWD:$PWD -w $PWD golang:1.18.1 go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/tmp/repro/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1501168033=/tmp/go-build -gno-record-gcc-switches"

What did you do?

https://go.dev/play/p/6a28XhlK8iQ

Sometimes it will hit on go.dev/play, more reliably reproduced by running locally.

I can avoid the problem by storing an initial value:

	var av atomic.Value
+ 	av.Store(1)

What did you expect to see?

Successful program execution.

What did you see instead?

panic: sync/atomic: compare and swap of inconsistently typed values

goroutine 14451 [running]:
sync/atomic.(*Value).CompareAndSwap(0xc000204b00?, {0xffffffffffffffff, 0x0}, {0x48fc40, 0x525828})
	/usr/local/go-faketime/src/sync/atomic/value.go:143 +0x17f
main.handleValue(0xc000204b20, 0x1)
	/tmp/sandbox4062856071/prog.go:20 +0xcd
main.dotest.func1(0x0?)
	/tmp/sandbox4062856071/prog.go:37 +0xa5
created by main.dotest
	/tmp/sandbox4062856071/prog.go:50 +0xda

Program exited.
@ianlancetaylor
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CC @randall77

@ianlancetaylor ianlancetaylor added NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. release-blocker labels Apr 28, 2022
@ianlancetaylor ianlancetaylor added this to the Go1.19 milestone Apr 28, 2022
@randall77
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Ah yes, looks like a "race" between my CL 241661, which renamed the first-store-in-progress marker, and CL 241678, which introduced new instances of the old marker. I think we just need to agree on the new one.

@gopherbot Please open a backport issue for 1.18.

@gopherbot gopherbot mentioned this issue Apr 29, 2022
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@gopherbot
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Backport issue(s) opened: #52615 (for 1.18).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

@gopherbot
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Change https://go.dev/cl/403094 mentions this issue: sync/atomic: use consistent first-store-in-progress marker

@dmitshur dmitshur added NeedsFix The path to resolution is known, but the work has not been done. and removed NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels May 4, 2022
hzyitc added a commit to hzyitc/go-notify that referenced this issue May 10, 2022
@hzyitc
Make sure go version >= 1.18.2
b736b46 
Due to the bug in golang/go#52612
@golang golang locked and limited conversation to collaborators May 4, 2023
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@dmitshur @wwade @ianlancetaylor @randall77 @gopherbot