Commit 6e39903c authored Jan 09, 2026 by Fushuai Wang Committed by Shuah Khan Jan 09, 2026

selftests/tracing: Fix test_multiple_writes stall

When /sys/kernel/tracing/buffer_size_kb is less than 12KB,
the test_multiple_writes test will stall and wait for more
input due to insufficient buffer space.

Check current buffer_size_kb value before the test. If it is
less than 12KB, it temporarily increase the buffer to 12KB,
and restore the original value after the tests are completed.

Link: https://lore.kernel.org/r/20260109033620.25727-1-fushuai.wang@linux.dev


Fixes: 37f46601 ("selftests/tracing: Add basic test for trace_marker_raw file")
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

parent 9ace4753

tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc

+17 −1

Original line number	Diff line number	Diff line
		@@ -89,6 +89,7 @@ test_buffer() {
		# The id must be four bytes, test that 3 bytes fails a write
		if echo -n abc > ./trace_marker_raw ; then
		echo "Too small of write expected to fail but did not"
		echo ${ORIG} > buffer_size_kb
		exit_fail
		fi

		@@ -99,9 +100,24 @@ test_buffer() {

		if write_buffer 0xdeadbeef $size ; then
		echo "Too big of write expected to fail but did not"
		echo ${ORIG} > buffer_size_kb
		exit_fail
		fi
		}

		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
		test_multiple_writes
		if ! test_multiple_writes; then
		echo ${ORIG} > buffer_size_kb
		exit_fail
		fi

		echo ${ORIG} > buffer_size_kb