cache/provider: use lock correctly #4168
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even checking if the file-lock object is non-nil needs
to be guarded with the lock
`go test -race` output:
```
==================
WARNING: DATA RACE
Read at 0x00c0005283f0 by goroutine 17:
github.com/linuxkit/linuxkit/src/cmd/linuxkit/cache.(*Provider).Lock()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/cache/provider.go:57 +0x55
github.com/linuxkit/linuxkit/src/cmd/linuxkit/cache.(*Provider).Index()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/cache/provider.go:47 +0x47
github.com/linuxkit/linuxkit/src/cmd/linuxkit/cache.(*Provider).FindDescriptor()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/cache/find.go:86 +0x46
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.(*dockerRunnerImpl).build()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/dockerimpl.go:683 +0x2a90
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.(*dockerRunnerImpl).builder()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/dockerimpl.go:245 +0x748
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.(*dockerRunnerImpl).build()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/dockerimpl.go:507 +0xec
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.Pkg.buildArch()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/build.go:718 +0x13cf
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.Pkg.Build()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/build.go:495 +0x4b64
bpftrace-compiler.(*imageBuilder).buildPkgs()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild.go:150 +0xf2d
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.WalkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:400 +0x89
bpftrace-compiler.hashDir()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/util.go:103 +0x2ae
bpftrace-compiler.(*imageBuilder).buildPkgs()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild.go:96 +0x144
bpftrace-compiler.TestCreateMobyConfig()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild_test.go:14 +0x26f
testing.tRunner()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1792 +0x225
testing.(*T).Run.gowrap1()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1851 +0x44
Previous write at 0x00c0005283f0 by goroutine 65:
github.com/linuxkit/linuxkit/src/cmd/linuxkit/cache.(*Provider).Lock()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/cache/provider.go:67 +0x2da
github.com/linuxkit/linuxkit/src/cmd/linuxkit/cache.(*Provider).ImageLoad()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/cache/write.go:157 +0x279
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.Pkg.buildArch.func2()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/build.go:697 +0x86
golang.org/x/sync/errgroup.(*Group).Go.func1()
/home/runner/go/pkg/mod/golang.org/x/[email protected]/errgroup/errgroup.go:93 +0x91
Goroutine 17 (running) created at:
testing.(*T).Run()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1851 +0x8f2
testing.runTests.func1()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:2279 +0x85
testing.tRunner()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1792 +0x225
testing.runTests()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:2277 +0x96c
testing.(*M).Run()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:2142 +0xeea
main.main()
_testmain.go:69 +0x164
Goroutine 65 (running) created at:
golang.org/x/sync/errgroup.(*Group).Go()
/home/runner/go/pkg/mod/golang.org/x/[email protected]/errgroup/errgroup.go:78 +0x124
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.Pkg.buildArch()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/build.go:696 +0xb05
github.com/linuxkit/linuxkit/src/cmd/linuxkit/pkglib.Pkg.Build()
/home/runner/go/pkg/mod/github.com/linuxkit/linuxkit/src/cmd/[email protected]/pkglib/build.go:495 +0x4b64
bpftrace-compiler.(*imageBuilder).buildPkgs()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild.go:150 +0xf2d
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:310 +0x84
path/filepath.walkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:332 +0x39e
path/filepath.WalkDir()
/opt/hostedtoolcache/go/1.24.6/x64/src/path/filepath/path.go:400 +0x89
bpftrace-compiler.hashDir()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/util.go:103 +0x2ae
bpftrace-compiler.(*imageBuilder).buildPkgs()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild.go:96 +0x144
bpftrace-compiler.TestCreateMobyConfig()
/home/runner/work/eve/eve/eve-tools/bpftrace-compiler/pkgbuild_test.go:14 +0x26f
testing.tRunner()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1792 +0x225
testing.(*T).Run.gowrap1()
/opt/hostedtoolcache/go/1.24.6/x64/src/testing/testing.go:1851 +0x44
==================
```
Signed-off-by: Christoph Ostarek <[email protected]>
Collaborator
|
I don't get why this works. The mutex only helps in the same process, yet a lockfile is meant to be across processes, so why would the mutex matter? I don't object to it, so happy to accept it, but why does it help? |
deitch
approved these changes
Sep 2, 2025
Contributor
Author
Apparently two goroutines in the same process can get to the |
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even checking if the file-lock object is non-nil needs to be guarded with the lock
go test -raceoutput:- What I did
Include checking for file-lock object in mutex.
- How I did it
Just must locking the mutex up.
- How to verify it
Unfortunately I was unable to reproduce it locally, I only saw it in "Go Tests" pipeline of: lf-edge/eve#5201
The test it is running is:
go test -v -race -run=TestCreateMobyConfig- Description for the changelog
Fix race condition that is rarely triggered
- A picture of a cute animal (not mandatory but encouraged)