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c8bd596f93
linux/tools/testing/selftests
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Michael Ellerman c8bd596f93 selftests/harness: Flush stdout before forking 
The test harness forks() a child to run each test. Both the parent and
the child print to stdout using libc functions. That can lead to
duplicated (or more) output if the libc buffers are not flushed before
forking.

It's generally not seen when running programs directly, because stdout
will usually be line buffered when it's pointing to a terminal.

This was noticed when running the seccomp_bpf test, eg:

  $ ./seccomp_bpf | tee test.log
  $ grep -c "TAP version 13" test.log
  2

But we only expect the TAP header to appear once.

It can be exacerbated using stdbuf to increase the buffer size:

  $ stdbuf -o 1MB ./seccomp_bpf > test.log
  $ grep -c "TAP version 13" test.log
  13

The fix is simple, we just flush stdout & stderr before fork. Usually
stderr is unbuffered, but that can be changed, so flush it as well
just to be safe.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2020-09-17 17:33:39 -06:00
..
android
arm64 kselftest: arm64: Remove redundant clean target 2020-06-24 14:25:59 +01:00
bpf selftests/bpf: Fix silent Makefile output 2020-08-07 18:52:32 +02:00
breakpoints selftests: breakpoints: do not use ksft_exit_skip after ksft_set_plan 2020-07-06 15:47:48 -06:00
capabilities
cgroup kselftests: cgroup: add perpcu memory accounting test 2020-08-12 10:57:55 -07:00
clone3 linux-kselftest-5.9-rc1 2020-08-05 10:28:25 -07:00
core tests: add CLOSE_RANGE_UNSHARE tests 2020-06-17 00:07:38 +02:00
cpu-hotplug
cpufreq
dmabuf-heaps
drivers selftests: mlxsw: RED: Test offload of trapping on RED qevents 2020-08-03 18:06:46 -07:00
efivarfs
exec selftests/exec: add file type errno tests 2020-08-14 19:56:56 -07:00
filesystems selftests/binderfs: Fix harness API usage 2020-07-06 15:59:16 -06:00
firmware selftest/firmware: Add selftest timeout in settings 2020-07-25 12:05:20 +02:00
fpu selftests/fpu: Add an FPU selftest 2020-06-29 10:02:23 +02:00
ftrace selftests/ftrace: Support ":README" suffix for requires 2020-06-16 10:42:47 -06:00
futex
gpio
ia64
intel_pstate
ipc
ir
kcmp
kexec
kmod selftests: kmod: use variable NAME in kmod_test_0001() 2020-08-12 10:58:01 -07:00
kselftest Driver core changes for 5.9-rc1 2020-08-05 11:52:17 -07:00
kvm KVM: nVMX: check for invalid hdr.vmx.flags 2020-07-27 09:04:50 -04:00
lib lib: make a test module with set/clear bit 2020-06-04 19:06:25 -07:00
livepatch selftests/livepatch: adopt to newer sysctl error format 2020-07-15 08:54:35 +02:00
lkdtm lkdtm: Make arch-specific tests always available 2020-06-29 18:41:39 +02:00
locking
media_tests
membarrier
memfd
memory-hotplug
mincore selftests: add mincore() tests 2020-08-07 11:33:27 -07:00
mount
mqueue
net mptcp: more stable diag self-tests 2020-08-07 17:25:38 -07:00
netfilter selftests: netfilter: add meta iif/oif match test 2020-08-03 12:02:22 +02:00
nsfs
ntb NTB: ntb_test: Fix bug when counting remote files 2020-06-05 20:02:09 -04:00
openat2
pid_namespace selftests: Remove unneeded selftest API headers 2020-07-06 15:59:07 -06:00
pidfd linux-kselftest-5.9-rc1 2020-08-05 10:28:25 -07:00
powerpc selftests/powerpc: Fix pkey syscall redefinitions 2020-08-05 10:14:03 +10:00
prctl
proc
pstore pstore/platform: Use backend name for console registration 2020-05-30 10:34:02 -07:00
ptp testptp: add new options for perout phase and pulse width 2020-07-20 18:04:59 -07:00
ptrace
rcutorture Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD 2020-06-29 12:03:15 -07:00
resctrl
rseq
rtc
safesetid
seccomp Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
sigaltstack selftests: sigaltstack: do not use ksft_exit_skip after ksft_set_plan 2020-07-06 15:57:15 -06:00
size
sparc64
splice selftests: splice: Check behavior of full and short splices 2020-08-07 10:50:11 -07:00
static_keys
sync selftests: sync_test: do not use ksft_exit_skip after ksft_set_plan 2020-07-06 15:57:28 -06:00
sysctl linux-kselftest-5.8-rc1 2020-06-09 10:03:12 -07:00
tc-testing tc-testing: Add tdc to kselftests 2020-07-20 18:29:37 -07:00
timens selftests/timens: handle a case when alarm clocks are not supported 2020-05-22 13:29:55 -06:00
timers selftests/timers: Turn off timeout setting 2020-08-20 15:49:28 -06:00
tmpfs
tpm2 selftests: tpm: upgrade TPM2 tests from Python 2 to Python 3 2020-07-06 14:20:35 -06:00
uevent selftests: Remove unneeded selftest API headers 2020-07-06 15:59:07 -06:00
user
vDSO selftests: vdso: Add a selftest for vDSO getcpu() 2020-05-22 11:05:07 -06:00
vm mm/migrate: add migrate-shared test for migrate_vma_*() 2020-08-12 10:57:56 -07:00
watchdog
wireguard wireguard: device: avoid circular netns references 2020-06-23 14:50:34 -07:00
x86 Support for FSGSBASE. Almost 5 years after the first RFC to support it, 2020-08-04 21:16:22 -07:00
zram
.gitignore
gen_kselftest_tar.sh selftests: introduce gen_tar Makefile target 2020-05-19 16:11:46 -06:00
kselftest_deps.sh
kselftest_harness.h selftests/harness: Flush stdout before forking 2020-09-17 17:33:39 -06:00
kselftest_install.sh
kselftest_module.h
kselftest.h linux-kselftest-5.9-rc1 2020-08-05 10:28:25 -07:00
lib.mk selftests: fix condition in run_tests 2020-07-07 14:11:31 -06:00
Makefile selftests: add mincore() tests 2020-08-07 11:33:27 -07:00