[DTrace-devel] [PATCH] test: Check tid value

[Kris Van Hees]

On Mon, Feb 24, 2025 at 03:19:22PM -0500, eugene.loh at oracle.com wrote:
> 
> We were checking the built-in variable tid simply by testing
> that we could print it and its value was not -1.
> 
> Add a test that confirms the value is actually correct;
> compare to C output of gettid().
> 
> In line with other similar tests, also check for the profile
> provider.
> 
> While we're at it, check the pid value and the pthread_t value
> returned via pthread_create().
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

> ---
>  test/unittest/builtinvar/tst.tid_pid.r  |   1 +
>  test/unittest/builtinvar/tst.tid_pid.sh | 126 ++++++++++++++++++++++++
>  2 files changed, 127 insertions(+)
>  create mode 100644 test/unittest/builtinvar/tst.tid_pid.r
>  create mode 100755 test/unittest/builtinvar/tst.tid_pid.sh
> 
> diff --git a/test/unittest/builtinvar/tst.tid_pid.r b/test/unittest/builtinvar/tst.tid_pid.r
> new file mode 100644
> index 000000000..2e9ba477f
> --- /dev/null
> +++ b/test/unittest/builtinvar/tst.tid_pid.r
> @@ -0,0 +1 @@
> +success
> diff --git a/test/unittest/builtinvar/tst.tid_pid.sh b/test/unittest/builtinvar/tst.tid_pid.sh
> new file mode 100755
> index 000000000..7ff0227fe
> --- /dev/null
> +++ b/test/unittest/builtinvar/tst.tid_pid.sh
> @@ -0,0 +1,126 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +CC=/usr/bin/gcc
> +
> +DIRNAME="$tmpdir/builtinvar-tid_pid.$$.$RANDOM"
> +mkdir -p $DIRNAME
> +cd $DIRNAME
> +
> +# Create trigger program.
> +
> +cat << EOF > main.c
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <sys/syscall.h>
> +#include <pthread.h>
> +
> +/* Provide an implementation in case glibc is too old. */
> +pid_t gettid(void)
> +{
> +        return syscall(__NR_gettid);
> +}
> +
> +static void * foo(void *arg) {
> +	int i = 0;
> +
> +	/*
> +	 * Each thread reports the pid and tid values it expects.
> +	 * (Expect the same values for both the pid and profile probes.)
> +	 */
> +	printf("pid     probe expect pid %d tid %d\n", getpid(), gettid());
> +	printf("profile probe expect pid %d tid %d\n", getpid(), gettid());
> +	fflush(stdout);
> +
> +	/* Wait endlessly.  DTrace will kill me when it is done. */
> +	while (i < 2)
> +		i ^= 1;
> +
> +	return 0;
> +}
> +
> +int main(int c, char **v) {
> +	pthread_t mythr;
> +
> +	/* Create a thread. */
> +	pthread_create(&mythr, NULL, &foo, NULL);
> +
> +	/* Also report the pthread_t. */
> +	printf("created pthread_t %lld\n\n", mythr);
> +	fflush(stdout);
> +
> +	/* Wait endlessly.  DTrace will kill me when it is done. */
> +	pthread_join(mythr, NULL);
> +
> +	return 0;
> +}
> +EOF
> +
> +# Compile the trigger program.
> +
> +$CC $test_cppflags main.c -lpthread
> +if [ $? -ne 0 ]; then
> +    echo compilation failed
> +    exit 1
> +fi
> +
> +# Run DTrace.
> +
> +rm -f C.out D.out
> +$dtrace $dt_flags -o D.out -c ./a.out -qn '
> +/* Report pid and tid from a pid-provider probe. */
> +pid$target:a.out:foo:entry
> +{
> +	self->mypid = pid;
> +	printf("pid     probe expect pid %d tid %d\n", pid, tid);
> +}
> +
> +/* Report pid and tid from a profile-provider probe.  Look for the thread we created. */
> +profile:::profile-1s
> +/self->mypid != 0/
> +{
> +	printf("profile probe expect pid %d tid %d\n", pid, tid);
> +	exit(0);
> +}
> +
> +/* While we are at it, check the pthread_t returned via pthread_create(). */
> +pid$target::pthread_create:entry
> +{
> +	self->thrid_p = (uintptr_t) arg0;
> +}
> +pid$target::pthread_create:return
> +{
> +	printf("created pthread_t %lld\n", *((long long *)copyin(self->thrid_p, sizeof(long long *))));
> +	self->thrid_p = 0
> +}' |& sort > C.out
> +if [ $? -ne 0 ]; then
> +	echo DTrace failed
> +	echo ==== C.out
> +	cat C.out
> +	echo ==== D.out
> +	cat D.out
> +	exit 1
> +fi
> +
> +# Compare the C and D output.
> +
> +sort D.out > D.out.sorted
> +if ! diff -q C.out D.out.sorted ; then
> +	echo ERROR: mismatch
> +	echo ==== C.out
> +	cat C.out
> +	echo ==== D.out
> +	cat D.out.sorted
> +	echo ==== diff
> +	diff C.out D.out.sorted
> +	exit 1
> +fi
> +
> +echo success
> +exit 0
> -- 
> 2.43.5
> 
>