From: Wen Yang <wen.yang@linux.dev>
To: Gabriele Monaco <gmonaco@redhat.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nam Cao <namcao@linutronix.de>,
Thomas Weissschuh <thomas.weissschuh@linutronix.de>,
Tomas Glozar <tglozar@redhat.com>, John Kacur <jkacur@redhat.com>
Subject: Re: [PATCH v5 13/17] rv: Add KUnit mock for current
Date: Thu, 30 Jul 2026 02:17:31 +0800 [thread overview]
Message-ID: <38a2480b-b420-4b14-9793-5ab3d7cfb2b9@linux.dev> (raw)
In-Reply-To: <20260723074534.43521-14-gmonaco@redhat.com>
On 7/23/26 15:45, Gabriele Monaco wrote:
> Some monitors do not only rely on tracepoint arguments but also on the
> currently executing task.
> This makes it more challenging to mock events in KUnit.
>
> Define wrapper functions around current, the functionality is mocked
> only during KUnit, an additional function call is avoided using a static
> branch unless any (even unrelated) KUnit test is running.
>
> Rely on a global mock_current variable that is set only by the RV KUnit
> tests and cleared on teardown. Unrelated KUnit tests that happen to
> trigger RV handlers would see it null and use current.
>
> Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
> ---
>
> Notes:
> V5:
> * Drop static stub from current to avoid issues with unrelated KUnit tests
>
> include/rv/da_monitor.h | 1 +
> include/rv/kunit.h | 14 +++++++++-
> include/rv/ltl_monitor.h | 1 +
> kernel/trace/rv/Kconfig | 3 +++
> .../trace/rv/monitors/pagefault/pagefault.c | 2 +-
> kernel/trace/rv/monitors/sleep/sleep.c | 24 ++++++++---------
> kernel/trace/rv/rv.c | 26 +++++++++++++++++++
> kernel/trace/rv/rv_monitors_test.c | 1 +
> 8 files changed, 58 insertions(+), 14 deletions(-)
>
> diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h
> index 773564720ba1..9f7ba443d777 100644
> --- a/include/rv/da_monitor.h
> +++ b/include/rv/da_monitor.h
> @@ -16,6 +16,7 @@
>
> #include <rv/automata.h>
> #include <linux/rv.h>
> +#include <rv/kunit.h>
> #include <linux/stringify.h>
> #include <linux/bug.h>
> #include <linux/sched.h>
> diff --git a/include/rv/kunit.h b/include/rv/kunit.h
> index ff98b5137285..31e0b93c40ea 100644
> --- a/include/rv/kunit.h
> +++ b/include/rv/kunit.h
> @@ -2,7 +2,10 @@
> /*
> * Copyright (C) 2026-2029 Red Hat, Inc. Gabriele Monaco <gmonaco@redhat.com>
> *
> - * Declaration of utilities to run KUnit tests.
> + * Declaration of wrappers to allow mocking core functionality, like current,
> + * and other testing utilities.
> + * Necessary only when mocking may be needed. If the RV KUnit test is
> + * enabled, the wrappers incur an additional function call overhead.
> */
>
> #ifndef _RV_KUNIT_H
> @@ -57,5 +60,14 @@ void prepare_test(struct kunit *test, const struct rv_kunit_mon *mon);
> void teardown_test(void *arg);
> struct task_struct *rv_kunit_alloc_mock_task(struct kunit *test);
>
> +void rv_mock_current(struct task_struct *tsk);
> +struct task_struct *rv_get_mock_current(void);
> +
> +#define rv_get_current() (unlikely(kunit_get_current_test()) ? rv_get_mock_current() : current)
> +
> +#else /* !CONFIG_RV_MONITORS_KUNIT_TEST */
> +
> +#define rv_get_current() current
> +
> #endif /* CONFIG_RV_MONITORS_KUNIT_TEST */
> #endif /* _RV_KUNIT_H */
> diff --git a/include/rv/ltl_monitor.h b/include/rv/ltl_monitor.h
> index 56e83edcf0c4..d7dc01db4dd9 100644
> --- a/include/rv/ltl_monitor.h
> +++ b/include/rv/ltl_monitor.h
> @@ -9,6 +9,7 @@
> #include <linux/stringify.h>
> #include <linux/seq_buf.h>
> #include <rv/instrumentation.h>
> +#include <rv/kunit.h>
> #include <trace/events/task.h>
> #include <trace/events/sched.h>
>
> diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
> index 34c1feb35a9b..da905de6c4e8 100644
> --- a/kernel/trace/rv/Kconfig
> +++ b/kernel/trace/rv/Kconfig
> @@ -121,4 +121,7 @@ config RV_MONITORS_KUNIT_TEST
> These tests verify that monitors correctly detect violations by
> triggering fake events and validating the expected reactions.
>
> + Enabling this may slightly increase overhead of some monitors if any
> + unrelated KUnit test is running.
> +
> If unsure, say N.
> diff --git a/kernel/trace/rv/monitors/pagefault/pagefault.c b/kernel/trace/rv/monitors/pagefault/pagefault.c
> index 5e1a2a606783..e52500fd2de0 100644
> --- a/kernel/trace/rv/monitors/pagefault/pagefault.c
> +++ b/kernel/trace/rv/monitors/pagefault/pagefault.c
> @@ -38,7 +38,7 @@ static void ltl_atoms_init(struct task_struct *task, struct ltl_monitor *mon, bo
> static void handle_page_fault(void *data, unsigned long address, struct pt_regs *regs,
> unsigned long error_code)
> {
> - ltl_atom_pulse(current, LTL_PAGEFAULT, true);
> + ltl_atom_pulse(rv_get_current(), LTL_PAGEFAULT, true);
> }
>
> static int enable_pagefault(void)
> diff --git a/kernel/trace/rv/monitors/sleep/sleep.c b/kernel/trace/rv/monitors/sleep/sleep.c
> index 12328ce663f5..71d2005ce520 100644
> --- a/kernel/trace/rv/monitors/sleep/sleep.c
> +++ b/kernel/trace/rv/monitors/sleep/sleep.c
> @@ -102,7 +102,7 @@ static void handle_sched_waking(void *data, struct task_struct *task)
> if (this_cpu_read(hardirq_context)) {
> ltl_atom_pulse(task, LTL_WOKEN_BY_HARDIRQ, true);
> } else if (in_task()) {
> - if (current->prio <= task->prio)
> + if (rv_get_current()->prio <= task->prio)
> ltl_atom_pulse(task, LTL_WOKEN_BY_EQUAL_OR_HIGHER_PRIO, true);
> } else if (in_nmi()) {
> ltl_atom_pulse(task, LTL_WOKEN_BY_NMI, true);
> @@ -112,12 +112,12 @@ static void handle_sched_waking(void *data, struct task_struct *task)
> static void handle_contention_begin(void *data, void *lock, unsigned int flags)
> {
> if (flags & LCB_F_RT)
> - ltl_atom_update(current, LTL_BLOCK_ON_RT_MUTEX, true);
> + ltl_atom_update(rv_get_current(), LTL_BLOCK_ON_RT_MUTEX, true);
> }
>
> static void handle_contention_end(void *data, void *lock, int ret)
> {
> - ltl_atom_update(current, LTL_BLOCK_ON_RT_MUTEX, false);
> + ltl_atom_update(rv_get_current(), LTL_BLOCK_ON_RT_MUTEX, false);
> }
>
> static void handle_sys_enter(void *data, struct pt_regs *regs, long id)
> @@ -126,7 +126,7 @@ static void handle_sys_enter(void *data, struct pt_regs *regs, long id)
> unsigned long args[6];
> int op, cmd;
>
> - mon = ltl_get_monitor(current);
> + mon = ltl_get_monitor(rv_get_current());
>
> switch (id) {
> #ifdef __NR_clock_nanosleep
> @@ -135,11 +135,11 @@ static void handle_sys_enter(void *data, struct pt_regs *regs, long id)
> #ifdef __NR_clock_nanosleep_time64
> case __NR_clock_nanosleep_time64:
> #endif
> - syscall_get_arguments(current, regs, args);
> + syscall_get_arguments(rv_get_current(), regs, args);
> ltl_atom_set(mon, LTL_NANOSLEEP_CLOCK_MONOTONIC, args[0] == CLOCK_MONOTONIC);
> ltl_atom_set(mon, LTL_NANOSLEEP_CLOCK_TAI, args[0] == CLOCK_TAI);
> ltl_atom_set(mon, LTL_NANOSLEEP_TIMER_ABSTIME, args[1] == TIMER_ABSTIME);
> - ltl_atom_update(current, LTL_CLOCK_NANOSLEEP, true);
> + ltl_atom_update(rv_get_current(), LTL_CLOCK_NANOSLEEP, true);
> break;
>
> #ifdef __NR_futex
> @@ -148,25 +148,25 @@ static void handle_sys_enter(void *data, struct pt_regs *regs, long id)
> #ifdef __NR_futex_time64
> case __NR_futex_time64:
> #endif
> - syscall_get_arguments(current, regs, args);
> + syscall_get_arguments(rv_get_current(), regs, args);
> op = args[1];
> cmd = op & FUTEX_CMD_MASK;
>
> switch (cmd) {
> case FUTEX_LOCK_PI:
> case FUTEX_LOCK_PI2:
> - ltl_atom_update(current, LTL_FUTEX_LOCK_PI, true);
> + ltl_atom_update(rv_get_current(), LTL_FUTEX_LOCK_PI, true);
> break;
> case FUTEX_WAIT:
> case FUTEX_WAIT_BITSET:
> case FUTEX_WAIT_REQUEUE_PI:
> - ltl_atom_update(current, LTL_FUTEX_WAIT, true);
> + ltl_atom_update(rv_get_current(), LTL_FUTEX_WAIT, true);
> break;
> }
> break;
> #ifdef __NR_epoll_wait
> case __NR_epoll_wait:
> - ltl_atom_update(current, LTL_EPOLL_WAIT, true);
> + ltl_atom_update(rv_get_current(), LTL_EPOLL_WAIT, true);
> break;
> #endif
> }
> @@ -174,7 +174,7 @@ static void handle_sys_enter(void *data, struct pt_regs *regs, long id)
>
> static void handle_sys_exit(void *data, struct pt_regs *regs, long ret)
> {
> - struct ltl_monitor *mon = ltl_get_monitor(current);
> + struct ltl_monitor *mon = ltl_get_monitor(rv_get_current());
>
> ltl_atom_set(mon, LTL_FUTEX_LOCK_PI, false);
> ltl_atom_set(mon, LTL_FUTEX_WAIT, false);
> @@ -182,7 +182,7 @@ static void handle_sys_exit(void *data, struct pt_regs *regs, long ret)
> ltl_atom_set(mon, LTL_NANOSLEEP_CLOCK_TAI, false);
> ltl_atom_set(mon, LTL_NANOSLEEP_TIMER_ABSTIME, false);
> ltl_atom_set(mon, LTL_EPOLL_WAIT, false);
> - ltl_atom_update(current, LTL_CLOCK_NANOSLEEP, false);
> + ltl_atom_update(rv_get_current(), LTL_CLOCK_NANOSLEEP, false);
> }
>
> static void handle_kthread_stop(void *data, struct task_struct *task)
> diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c
> index cfe950fef3b4..4c7143961e6e 100644
> --- a/kernel/trace/rv/rv.c
> +++ b/kernel/trace/rv/rv.c
> @@ -893,4 +893,30 @@ void rv_clear_testing(struct kunit_suite *suite)
> mutex_unlock(&rv_interface_lock);
> }
> EXPORT_SYMBOL_IF_KUNIT(rv_clear_testing);
> +
> +/*
> + * rv_get_mock_current() is called only if we are running from a KUnit test.
> + * This can occur from a legitimate RV test or any unrelated test running when
> + * a real RV monitor is active and triggering events.
> + * We assume the former case is the only one where mock_current is not NULL and
> + * can occur only sequentially (KUnit doesn't run tests in parallel).
> + * We cannot rely on the test's context because there is no way to safely
> + * understand from which test we are running and KUnit utilities require
> + * locking, which is unsafe from NMI or scheduling context.
> + * Note that it is not possible for a real RV monitor to run when the RV KUnit
> + * tests are running (see rv_set_testing()).
> + */
> +static struct task_struct *mock_current;
> +
> +void rv_mock_current(struct task_struct *tsk)
> +{
> + mock_current = tsk;
> +}
> +EXPORT_SYMBOL_IF_KUNIT(rv_mock_current);
> +
> +struct task_struct *rv_get_mock_current(void)
> +{
> + return mock_current ?: current;
> +}
> +EXPORT_SYMBOL_GPL(rv_get_mock_current);
> #endif
rv_mock_current() uses EXPORT_SYMBOL_IF_KUNIT, but rv_get_mock_current()
uses EXPORT_SYMBOL_GPL. Both are defined inside the same
CONFIG_RV_MONITORS_KUNIT_TEST block, so rv_get_mock_current should use
EXPORT_SYMBOL_IF_KUNIT as well, otherwise it leaks a test-only symbol
into production builds.
With that fixed:
Reviewed-by: Wen Yang <wen.yang@linux.dev>
--
Best wishes,
Wen
next prev parent reply other threads:[~2026-07-29 18:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-23 7:45 [PATCH v5 00/17] rv: Add selftests to tools and KUnit tests Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 01/17] rv: Use generic rv_this for the rv_monitor variable in LTL Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 02/17] tools/rv: Fix exit status when monitor execution fails Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 03/17] verification/rvgen: Improve rv_dir discovery in RVGenerator Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 04/17] verification/rvgen: Use pathlib instead of os.path Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 05/17] verification/rvgen: Improve consistency in template files Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 06/17] tools/rv: Add selftests Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 07/17] verification/rvgen: Add golden and spec folders for tests Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 08/17] verification/rvgen: Add selftests Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 09/17] verification/rvgen: Add the rvgen kunit subcommand Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 10/17] verification/rvgen: Add selftests for rvgen kunit Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 11/17] rv: Export task monitor slot and react symbols Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 12/17] rv: Add KUnit tests for some DA/HA monitors Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 13/17] rv: Add KUnit mock for current Gabriele Monaco
2026-07-29 18:17 ` Wen Yang [this message]
2026-07-23 7:45 ` [PATCH v5 14/17] rv: Add KUnit tests for some LTL monitors Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 15/17] selftests/verification: Fix wrong errexit assumption Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 16/17] selftests/verification: Rearrange the wwnr_printk test Gabriele Monaco
2026-07-23 7:45 ` [PATCH v5 17/17] selftests/verification: Add selftests for deadline and stall monitors Gabriele Monaco
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