[PATCH] selftests/ftrace: Check exact trace_marker_raw payload lengths

[PATCH] selftests/ftrace: Check exact trace_marker_raw payload lengths

[CaoRuichuang]

From: Cao Ruichuang <create0818@163.com>

trace_marker_raw.tc currently depends on awk strtonum() and
assumes that the printed raw-data byte count is rounded up to four
bytes.

That makes the test fail on systems that use mawk, and it no longer
matches the raw_data trace output we want to validate after preserving
true payload lengths for long records.

Rewrite the test to capture a small sequence of raw marker writes and
check the exact number of printed payload bytes in order. While doing
that, use od for the endian probe, switch to a fixed raw marker id so
the test only varies payload length, and disable pause-on-trace while
streaming trace_pipe.

Signed-off-by: Cao Ruichuang <create0818@163.com>
---
 .../ftrace/test.d/00basic/trace_marker_raw.tc | 93 ++++++++++++-------
 1 file changed, 59 insertions(+), 34 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc b/tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc
index a2c42e13f..3b37890f8 100644
--- a/tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc
+++ b/tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc
@@ -1,11 +1,11 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 # description: Basic tests on writing to trace_marker_raw
-# requires: trace_marker_raw
+# requires: trace_marker_raw od:program
 # flags: instance
 
 is_little_endian() {
-	if lscpu | grep -q 'Little Endian'; then
+	if [ "$(printf '\001\000\000\000' | od -An -tu4 | tr -d '[:space:]')" = "1" ]; then
 		echo 1;
 	else
 		echo 0;
@@ -34,7 +34,7 @@ make_str() {
 
 	data=`printf -- 'X%.0s' $(seq $cnt)`
 
-	printf "${val}${data}"
+	printf "%b%s" "${val}" "${data}"
 }
 
 write_buffer() {
@@ -47,36 +47,68 @@ write_buffer() {
 
 
 test_multiple_writes() {
+	out_file=$TMPDIR/trace_marker_raw.out
+	match_file=$TMPDIR/trace_marker_raw.lines
+	wait_iter=0
+	pause_on_trace=
+
+	if [ -f options/pause-on-trace ]; then
+		pause_on_trace=`cat options/pause-on-trace`
+		echo 0 > options/pause-on-trace
+	fi
+
+	: > trace
+	cat trace_pipe > $out_file &
+	reader_pid=$!
+	sleep 1
+
+	# Write sizes that cover both the short and long raw-data encodings
+	# without overflowing the trace buffer before we can verify them.
+	for i in `seq 1 12`; do
+		write_buffer 0x12345678 $i
+	done
 
-	# Write a bunch of data where the id is the count of
-	# data to write
-	for i in `seq 1 10` `seq 101 110` `seq 1001 1010`; do
-		write_buffer $i $i
+	while [ "`grep -c ' buf:' $out_file 2> /dev/null || true`" -lt 12 ]; do
+		wait_iter=$((wait_iter + 1))
+		if [ $wait_iter -ge 10 ]; then
+			kill $reader_pid 2> /dev/null || true
+			wait $reader_pid 2> /dev/null || true
+			if [ -n "$pause_on_trace" ]; then
+				echo $pause_on_trace > options/pause-on-trace
+			fi
+			return 1
+		fi
+		sleep 1
 	done
 
 	# add a little buffer
 	echo stop > trace_marker
+	sleep 1
+	kill $reader_pid 2> /dev/null || true
+	wait $reader_pid 2> /dev/null || true
+	if [ -n "$pause_on_trace" ]; then
+		echo $pause_on_trace > options/pause-on-trace
+	fi
 
-	# Check to make sure the number of entries is the id (rounded up by 4)
-	awk '/.*: # [0-9a-f]* / {
-			print;
-			cnt = -1;
-			for (i = 0; i < NF; i++) {
-				# The counter is after the "#" marker
-				if ( $i == "#" ) {
-					i++;
-					cnt = strtonum("0x" $i);
-					num = NF - (i + 1);
-					# The number of items is always rounded up by 4
-					cnt2 = int((cnt + 3) / 4) * 4;
-					if (cnt2 != num) {
-						exit 1;
-					}
-					break;
-				}
-			}
-		}
-	// { if (NR > 30) { exit 0; } } ' trace_pipe;
+	grep ' buf:' $out_file > $match_file || return 1
+	if [ "`wc -l < $match_file`" -ne 12 ]; then
+		cat $match_file
+		return 1
+	fi
+
+	# Check to make sure the number of byte values matches the id exactly.
+	for expected in `seq 1 12`; do
+		line=`sed -n "${expected}p" $match_file`
+		if [ -z "$line" ]; then
+			return 1
+		fi
+		rest=${line#* buf: }
+		set -- $rest
+		if [ "$#" -ne "$expected" ]; then
+			echo "$line"
+			return 1
+		fi
+	done
 }
 
 
@@ -107,13 +139,6 @@ test_buffer() {
 
 ORIG=`cat buffer_size_kb`
 
-# test_multiple_writes test needs at least 12KB buffer
-NEW_SIZE=12
-
-if [ ${ORIG} -lt ${NEW_SIZE} ]; then
-	echo ${NEW_SIZE} > buffer_size_kb
-fi
-
 test_buffer
 if ! test_multiple_writes; then
 	echo ${ORIG} > buffer_size_kb
-- 
2.39.5 (Apple Git-154)

Re: [PATCH] selftests/ftrace: Check exact trace_marker_raw payload lengths

[Cao Ruichuang]

A follow-up on this patch: I am pausing it in its current form.

The exact payload-length checks here were based on my earlier
ring-buffer change, and Steven has rejected that direction because
the ring buffer is meant to keep the allocated size, not the
requested payload size.

So this selftest should not move forward as-is. If there is a real
fix, it needs to come from an event-specific change that explicitly
stores the true payload length where needed. I will revisit it only
from that direction.

Thanks,
Cao Ruichuang

Re: [PATCH] selftests/ftrace: Check exact trace_marker_raw payload lengths

[Steven Rostedt]

On Tue,  7 Apr 2026 18:12:45 +0800
CaoRuichuang <create0818@163.com> wrote:

> From: Cao Ruichuang <create0818@163.com>
> 
> trace_marker_raw.tc currently depends on awk strtonum() and
> assumes that the printed raw-data byte count is rounded up to four
> bytes.
> 
> That makes the test fail on systems that use mawk, and it no longer
> matches the raw_data trace output we want to validate after preserving
> true payload lengths for long records.
> 
> Rewrite the test to capture a small sequence of raw marker writes and
> check the exact number of printed payload bytes in order. While doing
> that, use od for the endian probe, switch to a fixed raw marker id so
> the test only varies payload length, and disable pause-on-trace while
> streaming trace_pipe.
> 

The tests are to validate the code and if the tests fail when the code is
working as designed, it is the test that is at fault, and the fix is to fix
the tests. Not to make the code match the test.

-- Steve