selftests: Remove forced unbuffering for test running

As it turns out, the "stdbuf" command will actually force all
subprocesses into unbuffered output, and some implementations of "echo"
turn into single-character writes, which utterly wrecks writes to /sys
and /proc files.

Instead, drop the "stdbuf" usage, and for any tests that want explicit
flushing between newlines, they'll have to add "fflush(stdout);" as
needed.

Reported-by: Takashi Iwai <tiwai@suse.de>
Fixes: 5c069b6dedef ("selftests: Move test output to diagnostic lines")
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh
index eff3ee3..00c9020 100644 (file)
--- a/tools/testing/selftests/kselftest/runner.sh
+++ b/tools/testing/selftests/kselftest/runner.sh
@@ -24,16 +24,6 @@ tap_prefix()
        fi
 }
 
-# If stdbuf is unavailable, we must fall back to line-at-a-time piping.
-tap_unbuffer()
-{
-       if ! which stdbuf >/dev/null ; then
-               "$@"
-       else
-               stdbuf -i0 -o0 -e0 "$@"
-       fi
-}
-
 run_one()
 {
        DIR="$1"
@@ -54,7 +44,7 @@ run_one()
                echo "not ok $test_num $TEST_HDR_MSG"
        else
                cd `dirname $TEST` > /dev/null
-               (((((tap_unbuffer ./$BASENAME_TEST 2>&1; echo $? >&3) |
+               (((((./$BASENAME_TEST 2>&1; echo $? >&3) |
                        tap_prefix >&4) 3>&1) |
                        (read xs; exit $xs)) 4>>"$logfile" &&
                echo "ok $test_num $TEST_HDR_MSG") ||