[LTP] ftrace: Add common library for C implementation

[linuxtestproject.agent@gmail.com]

Hi Praveen,

On Tue, Jun 9, 2026, Praveen K Pandey wrote:
> ftrace: Add common library for C implementation

--- [PATCH 1/5] ---

> -INSTALL_TARGETS         := *.sh ftrace_stress/*
> +# Filter out ftrace_lib from standalone build targets
> +FILTER_OUT_MAKE_TARGETS := ftrace_lib

Removing INSTALL_TARGETS here means the ftrace_stress/* helper
scripts are no longer installed, but ftrace_stress_test.sh still
exists and depends on them (it is not converted until patch 4/5).
This breaks the shell-based stress test at this intermediate
commit.

Moving this removal to patch 5/5 (where the helper scripts are
actually deleted) would preserve bisectability.

--- [PATCH 2/5] ---

> -ftrace_regression01	ftrace_regression01.sh
> -ftrace_regression02	ftrace_regression02.sh
> -ftrace-stress-test	ftrace_stress_test.sh 90
> +ftrace_regression01	ftrace_regression01
> +ftrace_regression02	ftrace_regression02
> +ftrace-stress-test	ftrace_stress_test

This patch converts only ftrace_regression01, but all three
runtest/tracing entries are updated to reference C binaries.
At this point ftrace_regression02 and ftrace_stress_test binaries
do not exist -- their .c files are added in patches 3/5 and 4/5
respectively.

After this commit, running ftrace_regression02 or ftrace-stress-test
from the runtest file will look for binaries that cannot be built.
Each conversion patch should only update its own runtest entry.

--- [PATCH 4/5] ---

> +static struct stress_test stress_tests[] = {
> +	{"current_tracer", "current_tracer", stress_current_tracer, 0},
> +	{"trace_pipe", "trace_pipe", stress_trace_pipe, 0},
> +	{"set_event", "events/enable", stress_set_event, 0},
> +	{"buffer_size_kb", "buffer_size_kb", stress_buffer_size, 0},
> +	{"tracing_on", "tracing_on", stress_tracing_on, 0},
> +	{"trace_options", "trace_options", stress_trace_options, 0},
> +	{"set_ftrace_filter", "set_ftrace_filter", stress_set_ftrace_filter, 0},

The original shell test exercised 17 ftrace interfaces concurrently:
trace_pipe, current_tracer, ftrace_enabled,
function_profile_enabled, set_event, set_ftrace_pid,
stack_max_size, stack_trace, trace, trace_clock, trace_options,
trace_stat, tracing_enabled, tracing_max_latency, tracing_on,
buffer_size_kb, tracing_cpumask, and set_ftrace_filter.

The C version implements 7 of these, dropping 10 stress targets.
Is the reduced coverage intentional? If so, it would be good to
note it in the commit message.

>  * Converted to C by: Praveen K Pandey <praveen@linux.ibm.com>
>  */
>
> +/*\
>  * ...
>  *    The test creates multiple threads that stress test different
>  *    ftrace interfaces concurrently for a specified duration.
>  *
>  *    Signed-off-by: Praveen K Pandey <praveen@linux.ibm.com>

The commit message states "Test timeout set to 300 seconds", but
the code has `.timeout = DEFAULT_TEST_DURATION + 30` which
evaluates to 90, not 300.

Verdict: Needs revision

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