cmd/cgo: ThreadSanitizer barks about data races in all.bash

[ALTree]

go version devel +b83f397 Wed Mar 2 19:32:41 2016 +0000 linux/amd64

I'm seeing this on tip:

##### ../misc/cgo/testasan

##### ../misc/cgo/testsanitizers
skipping msan tests: -fsanitize=memory not supported
==================
WARNING: ThreadSanitizer: data race (pid=2282)
  Write of size 4 at 0x0000006d20b8 by thread T2:
    #0 setVal /home/alberto/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x00000044b9b0)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/alberto/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x00000044ba31)
    #2 runtime.asmcgocall <null> (tsan+0x00000044782f)

  Previous write of size 4 at 0x0000006d20b8 by main thread:
    #0 setVal /home/alberto/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x00000044b9b0)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/alberto/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x00000044ba31)
    #2 runtime.asmcgocall <null> (tsan+0x00000044782f)

  Location is global 'val' of size 4 at 0x0000006d20b8 (tsan+0x0000006d20b8)

  Thread T2 (tid=2285, running) created by main thread at:
    #0 pthread_create <null> (libtsan.so.0+0x000000026e74)
    #1 _cgo_sys_thread_start /home/alberto/go/src/runtime/cgo/gcc_linux_amd64.c:75 (tsan+0x00000044bd3e)

SUMMARY: ThreadSanitizer: data race /home/alberto/go/misc/cgo/testsanitizers/tsan.go:22 setVal
==================
FAIL: tsan
==================
WARNING: ThreadSanitizer: data race (pid=2412)
  Write of size 4 at 0x0000006d2018 by thread T2:
    #0 setVal /home/alberto/go/misc/cgo/testsanitizers/tsan2.go:32 (tsan2+0x00000044ba90)
    #1 _cgo_b3c556dc7343_Cfunc_setVal /home/alberto/go/misc/cgo/testsanitizers/tsan2.go:106 (tsan2+0x00000044bc01)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044793f)

  Previous write of size 4 at 0x0000006d2018 by main thread:
    #0 run /home/alberto/go/misc/cgo/testsanitizers/tsan2.go:24 (tsan2+0x00000044baf9)
    #1 _cgo_b3c556dc7343_Cfunc_run /home/alberto/go/misc/cgo/testsanitizers/tsan2.go:92 (tsan2+0x00000044bbad)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044793f)

  Location is global 'val' of size 4 at 0x0000006d2018 (tsan2+0x0000006d2018)

  Thread T2 (tid=2416, running) created by main thread at:
    #0 pthread_create <null> (libtsan.so.0+0x000000026e74)
    #1 _cgo_sys_thread_start /home/alberto/go/src/runtime/cgo/gcc_linux_amd64.c:75 (tsan2+0x00000044bf0e)

SUMMARY: ThreadSanitizer: data race /home/alberto/go/misc/cgo/testsanitizers/tsan2.go:32 setVal
==================
FAIL: tsan2
2016/03/02 20:59:43 Failed: exit status 1

$ uname -a
Linux gauss 4.3.0-1-amd64 #1 SMP Debian 4.3.5-1 (2016-02-06) x86_64 GNU/Linux
$ gcc --version
gcc (Debian 5.3.1-8) 5.3.1 20160205

[ALTree]

Unsurprisingly, c8ef0df is the first commit that triggers the failure.

[ianlancetaylor]

Do you have clang installed on your system? Which version?

[ALTree]

I don't have clang installed.

[shuLhan]

I can confirm this in Linux with commit 686fbdb.

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

go version devel +686fbdb Thu Mar 3 18:03:45 2016 +0000 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/ms/go/work"
GORACE=""
GOROOT="/home/ms/git/go"
GOTOOLDIR="/home/ms/git/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build621757699=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

• What did you do?
  (Use play.golang.org to provide a runnable example, if possible.)

$ cd src && ./all.bash

• What did you expect to see?

All test passed and new Go binaries installed.

• What did you see instead?

Skipping msan tests: -fsanitize=memory not supported
==================
WARNING: ThreadSanitizer: data race (pid=24774)
  Write of size 4 at 0x0000006d20b8 by thread T2:
    #0 setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x00000044b990)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x00000044ba11)
    #2 runtime.asmcgocall <null> (tsan+0x00000044780f)

  Previous write of size 4 at 0x0000006d20b8 by main thread:
    #0 setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x00000044b990)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x00000044ba11)
    #2 runtime.asmcgocall <null> (tsan+0x00000044780f)

  Location is global 'val' of size 4 at 0x0000006d20b8 (tsan+0x0000006d20b8)

  Thread T2 (tid=24778, running) created by main thread at:
    #0 pthread_create /build/gcc/src/gcc-5-20160209/libsanitizer/tsan/tsan_interceptors.cc:895 (libtsan.so.0+0x0000000274d7)
    #1 _cgo_sys_thread_start /home/ms/git/go/src/runtime/cgo/gcc_linux_amd64.c:75 (tsan+0x00000044bd1e)

SUMMARY: ThreadSanitizer: data race /home/ms/git/go/misc/cgo/testsanitizers/tsan.go:22 setVal
==================
FAIL: tsan
==================
WARNING: ThreadSanitizer: data race (pid=24864)
  Write of size 4 at 0x0000006d2018 by thread T2:
    #0 setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan2.go:32 (tsan2+0x00000044ba70)
    #1 _cgo_b3c556dc7343_Cfunc_setVal /home/ms/git/go/misc/cgo/testsanitizers/tsan2.go:106 (tsan2+0x00000044bbe1)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044791f)

  Previous write of size 4 at 0x0000006d2018 by main thread:
    #0 run /home/ms/git/go/misc/cgo/testsanitizers/tsan2.go:24 (tsan2+0x00000044bad9)
    #1 _cgo_b3c556dc7343_Cfunc_run /home/ms/git/go/misc/cgo/testsanitizers/tsan2.go:92 (tsan2+0x00000044bb8d)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044791f)

  Location is global 'val' of size 4 at 0x0000006d2018 (tsan2+0x0000006d2018)

  Thread T2 (tid=24867, running) created by main thread at:
    #0 pthread_create /build/gcc/src/gcc-5-20160209/libsanitizer/tsan/tsan_interceptors.cc:895 (libtsan.so.0+0x0000000274d7)
    #1 _cgo_sys_thread_start /home/ms/git/go/src/runtime/cgo/gcc_linux_amd64.c:75 (tsan2+0x00000044beee)

SUMMARY: ThreadSanitizer: data race /home/ms/git/go/misc/cgo/testsanitizers/tsan2.go:32 setVal
==================
FAIL: tsan2
2016/03/04 01:10:19 Failed: exit status 1

##### ../misc/cgo/errors

##### ../misc/cgo/testsigfwd

##### ../test/bench/go1
testing: warning: no tests to run
PASS
ok      _/home/ms/git/go/test/bench/go1 2.233s

##### ../test
skipped due to earlier error
skipped due to earlier error
skipped due to earlier error
skipped due to earlier error
skipped due to earlier error

##### API check
skipped due to earlier error
2016/03/04 01:10:22 FAILED

[ianlancetaylor]

@shuLhan Same questions as above: do you have clang installed? What version? If clang is not installed, what version of GCC is installed? Thanks.

[shuLhan]

@ianlancetaylor,

Same questions as above: do you have clang installed? What version?

No.

If clang is not installed, what version of GCC is installed? Thanks.

gcc (GCC) 5.3.0
glibc 2.23-1

System: Linux xenom-bubu 4.4.3-1-ARCH #1 SMP PREEMPT x86_64 GNU/Linux

[shuLhan]

Just a side note, in case someone search and found this issue.

If you want to make all.bash works either,

• install clang and set CC=clang, or
• set CGO=0 (at current tip it has been changed to CGO_ENABLED) before running all.bash.

Build and test works with clang version 3.7.1.

[nadiasvertex]

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

go version devel +a145378 Mon Mar 21 20:24:06 2016 +0000 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH=""
GORACE=""
GOROOT="/home/christopher/workspace/go-official"
GOTOOLDIR="/home/christopher/workspace/go-official/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build420019199=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

1. What did you do?

Executed src/all.bash

1. What did you expect to see?

All tests passed.

1. What did you see instead?

##### ../misc/cgo/testsanitizers
skipping msan tests: -fsanitize=memory not supported
==================
WARNING: ThreadSanitizer: data race (pid=14437)
  Write of size 4 at 0x0000006b2e78 by thread T2:
    #0 setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x000000445070)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x0000004450f1)
    #2 runtime.asmcgocall <null> (tsan+0x00000044235f)

  Previous write of size 4 at 0x0000006b2e78 by main thread:
    #0 setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x000000445070)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x0000004450f1)
    #2 runtime.asmcgocall <null> (tsan+0x00000044235f)

  Location is global 'val' of size 4 at 0x0000006b2e78 (tsan+0x0000006b2e78)

  Thread T2 (tid=14440, running) created by main thread at:
    #0 pthread_create <null> (libtsan.so.0+0x000000027537)
    #1 _cgo_sys_thread_start /home/christopher/workspace/go-official/src/runtime/cgo/gcc_linux_amd64.c:73 (tsan+0x000000445471)

SUMMARY: ThreadSanitizer: data race /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan.go:22 setVal
==================
FAIL: tsan
==================
WARNING: ThreadSanitizer: data race (pid=14631)
  Write of size 4 at 0x0000006b3dd8 by thread T3:
    #0 setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan2.go:32 (tsan2+0x000000445150)
    #1 _cgo_b3c556dc7343_Cfunc_setVal /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan2.go:106 (tsan2+0x0000004452e1)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044246f)

  Previous write of size 4 at 0x0000006b3dd8 by main thread:
    #0 run /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan2.go:24 (tsan2+0x0000004451d9)
    #1 _cgo_b3c556dc7343_Cfunc_run /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan2.go:92 (tsan2+0x00000044528d)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044246f)

  Location is global '<null>' of size 0 at 0x000000000000 (tsan2+0x0000006b3dd8)

  Thread T3 (tid=14650, running) created by main thread at:
    #0 pthread_create <null> (libtsan.so.0+0x000000027537)
    #1 _cgo_sys_thread_start /home/christopher/workspace/go-official/src/runtime/cgo/gcc_linux_amd64.c:73 (tsan2+0x000000445661)

SUMMARY: ThreadSanitizer: data race /home/christopher/workspace/go-official/misc/cgo/testsanitizers/tsan2.go:32 setVal
==================
FAIL: tsan2
2016/03/21 18:56:53 Failed: exit status 1

I do not have clang installed. My gcc is:

gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.3.1-11ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.3.1 20160311 (Ubuntu 5.3.1-11ubuntu1) 

[rjammala]

I too see this on Ubuntu with gcc 5.3.1 20160320. clang is not installed.
I tried to build tip using go1.6
Here are the details:

$ uname -a
Linux ubuntu 4.4.0-15-generic #31-Ubuntu SMP Fri Mar 18 19:08:31 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

$ gcc --version
gcc (Ubuntu/Linaro 5.3.1-12ubuntu4) 5.3.1 20160320
Copyright (C) 2015 Free Software Foundation, Inc.

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/rjammalamadaka/gocode"
GORACE=""
GOROOT="/home/rjammalamadaka/go"
GOTOOLDIR="/home/rjammalamadaka/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build653676224=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

 ../misc/cgo/testasan

 ../misc/cgo/testsanitizers
skipping msan tests: -fsanitize=memory not supported
WARNING: ThreadSanitizer: data race (pid=33614)
  Write of size 4 at 0x0000006ace98 by thread T3:
    #0 setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x000000445350)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x0000004453d1)
    #2 runtime.asmcgocall <null> (tsan+0x00000044265f)

  Previous write of size 4 at 0x0000006ace98 by main thread:
    #0 setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan.go:22 (tsan+0x000000445350)
    #1 _cgo_82605fb7dc7c_Cfunc_setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan.go:96 (tsan+0x0000004453d1)
    #2 runtime.asmcgocall <null> (tsan+0x00000044265f)

  Location is global 'val' of size 4 at 0x0000006ace98 (tsan+0x0000006ace98)

  Thread T3 (tid=33619, running) created by main thread at:
    #0 pthread_create <null> (libtsan.so.0+0x000000027597)
    #1 _cgo_sys_thread_start /home/rjammalamadaka/go/src/runtime/cgo/gcc_linux_amd64.c:73 (tsan+0x000000445751)

SUMMARY: ThreadSanitizer: data race /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan.go:22 setVal
FAIL: tsan
WARNING: ThreadSanitizer: data race (pid=33736)
  Write of size 4 at 0x0000006acdf8 by thread T4:
    #0 setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan2.go:32 (tsan2+0x000000445430)
    #1 _cgo_b3c556dc7343_Cfunc_setVal /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan2.go:106 (tsan2+0x0000004455c1)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044276f)

  Previous write of size 4 at 0x0000006acdf8 by main thread:
    #0 run /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan2.go:24 (tsan2+0x0000004454b9)
    #1 _cgo_b3c556dc7343_Cfunc_run /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan2.go:92 (tsan2+0x00000044556d)
    #2 runtime.asmcgocall <null> (tsan2+0x00000044276f)

  Location is global '<null>' of size 0 at 0x000000000000 (tsan2+0x0000006acdf8)

  Thread T4 (tid=33741, running) created by thread T2 at:
    #0 pthread_create <null> (libtsan.so.0+0x000000027597)
    #1 _cgo_sys_thread_start /home/rjammalamadaka/go/src/runtime/cgo/gcc_linux_amd64.c:73 (tsan2+0x000000445941)

SUMMARY: ThreadSanitizer: data race /home/rjammalamadaka/go/misc/cgo/testsanitizers/tsan2.go:32 setVal
FAIL: tsan2
2016/03/28 12:03:22 Failed: exit status 1

[dvyukov]

@ianlancetaylor I think gcc does not support __has_feature feature used in src/cmd/cgo/out.go.
Maybe we can just look at presence of -fsanitize=thread flag? If compiler does not support -fsanitize=thread, then we will get compilation errors due to unsupported flag anyway.