On Wed, Dec 16, 2020 at 04:49:59PM +0100, Uladzislau Rezki wrote:
> > Add self tests for checking of RCU-tasks API functionality.
> > It covers:
> > - wait API functions;
> > - invoking/completion call_rcu_tasks*().
> >
> > Self-tests are run when CONFIG_PROVE_RCU kernel parameter is set.
> >
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> > ---
> > kernel/rcu/tasks.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 44 insertions(+)
> >
> > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > index 67a162949763..9407772780c1 100644
> > --- a/kernel/rcu/tasks.h
> > +++ b/kernel/rcu/tasks.h
> > @@ -1225,6 +1225,16 @@ void show_rcu_tasks_gp_kthreads(void)
> > }
> > #endif /* #ifndef CONFIG_TINY_RCU */
> >
> > +static struct rcu_head rhp;
> > +static int rcu_execurted_test_counter;
> > +static int rcu_run_test_counter;
> > +
> > +static void test_rcu_tasks_callback(struct rcu_head *r)
> > +{
> > + pr_info("RCU-tasks test callback executed %d\n",
> > + ++rcu_execurted_test_counter);
> > +}
> > +
> > void __init rcu_init_tasks_generic(void)
> > {
> > #ifdef CONFIG_TASKS_RCU
> > @@ -1238,7 +1248,41 @@ void __init rcu_init_tasks_generic(void)
> > #ifdef CONFIG_TASKS_TRACE_RCU
> > rcu_spawn_tasks_trace_kthread();
> > #endif
> > +
> > + if (IS_ENABLED(CONFIG_PROVE_RCU)) {
> > + pr_info("Running RCU-tasks wait API self tests\n");
> > +#ifdef CONFIG_TASKS_RCU
> > + rcu_run_test_counter++;
> > + call_rcu_tasks(&rhp, test_rcu_tasks_callback);
> > + synchronize_rcu_tasks();
> > +#endif
> > +
> > +#ifdef CONFIG_TASKS_RUDE_RCU
> > + rcu_run_test_counter++;
> > + call_rcu_tasks_trace(&rhp, test_rcu_tasks_callback);
> > + synchronize_rcu_tasks_rude();
> > +#endif
> > +
> > +#ifdef CONFIG_TASKS_TRACE_RCU
> > + rcu_run_test_counter++;
> > + call_rcu_tasks_trace(&rhp, test_rcu_tasks_callback);
> > + synchronize_rcu_tasks_trace();
> > +#endif
> > + }
> > +}
> > +
> > +static int rcu_tasks_verify_self_tests(void)
> > +{
> > + int ret = 0;
> > +
> > + if (rcu_run_test_counter != rcu_execurted_test_counter) {
> > + WARN_ON(1);
> > + ret = -1;
> > + }
> > +
> > + return ret;
> > }
> > +late_initcall(rcu_tasks_verify_self_tests);
> >
> > #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
> > static inline void rcu_tasks_bootup_oddness(void) {}
> Please find a v2 of the patch that is in question. First version
> uses the same rhp for all RCU flavors what is wrong. Initially
> i had three different one per one flavor. But for some reason
> end up with only one.
>
>
> >From e7c6096af5a7916f29c0b4b05e1644b3b3a6c589 Mon Sep 17 00:00:00 2001
> From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>
> Date: Wed, 9 Dec 2020 21:27:32 +0100
> Subject: [PATCH v2 1/1] rcu-tasks: Add RCU-tasks self tests
>
> This commit adds self tests for early-boot use of RCU-tasks grace periods.
> It tests all three variants (Rude, Tasks, and Tasks Trace) and covers
> both synchronous (e.g., synchronize_rcu_tasks()) and asynchronous (e.g.,
> call_rcu_tasks()) grace-period APIs.
>
> Self-tests are run only in kernels built with CONFIG_PROVE_RCU=y.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Much improved, thank you! A few more comments below.
> ---
> kernel/rcu/tasks.h | 69 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 69 insertions(+)
>
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index 36607551f966..7478d912734a 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -1224,6 +1224,35 @@ void show_rcu_tasks_gp_kthreads(void)
> }
> #endif /* #ifndef CONFIG_TINY_RCU */
>
> +struct test_desc {
Please use something like "struct rcu_tasks_test_desc" to help the poor
people who might need to grep for this. Feel free to shorten it, but
please make it descriptive and thus more likely to stay unique.
> + struct rcu_head rh;
> + const char *name;
> + bool run;
If you make this "bool notrun" you don't need to initialize.
> +};
> +
> +static struct test_desc tests[] = {
> + { .name = "call_rcu_tasks()" },
> + { .name = "call_rcu_rude()" },
> + { .name = "call_rcu_trace()" },
> +};
> +
> +static int rcu_executed_test_counter;
> +
> +static void test_rcu_tasks_callback(struct rcu_head *rhp)
> +{
struct rcu_tasks_test_desc *rttdp;
> + int i;
> +
> + pr_info("RCU-tasks test callback executed %d\n",
> + ++rcu_executed_test_counter);
rttdp = container_of(rhp, rh, struct rcu_tasks_test_desc);
rttdp->notrun = true;
Or I suppose:
container_of(rhp, rh, struct rcu_tasks_test_desc)->notrun = true;
Then the loop below can go away.
> +
> + for (i = 0; i < ARRAY_SIZE(tests); i++) {
> + if (rhp == &tests[i].rh) {
> + tests[i].run = false;
> + break;
> + }
> + }
> +}
> +
> void __init rcu_init_tasks_generic(void)
> {
> #ifdef CONFIG_TASKS_RCU
> @@ -1237,7 +1266,47 @@ void __init rcu_init_tasks_generic(void)
> #ifdef CONFIG_TASKS_TRACE_RCU
> rcu_spawn_tasks_trace_kthread();
> #endif
> +
> + // Run the self-tests.
> + if (IS_ENABLED(CONFIG_PROVE_RCU)) {
> + pr_info("Running RCU-tasks wait API self tests\n");
> +#ifdef CONFIG_TASKS_RCU
> + tests[0].run = true;
The s/run/notrun/ allows the three initializations of .run to go away.
> + call_rcu_tasks(&tests[0].rh, test_rcu_tasks_callback);
> + synchronize_rcu_tasks();
Why not reverse the order of these two statements? That would test
call_rcu_tasks*()'s ability to do a grace period on their own, without
help from the corresponding synchronize_rcu_tasks*().
> +#endif
> +
> +#ifdef CONFIG_TASKS_RUDE_RCU
> + tests[1].run = true;
> + call_rcu_tasks_rude(&tests[1].rh, test_rcu_tasks_callback);
> + synchronize_rcu_tasks_rude();
> +#endif
> +
> +#ifdef CONFIG_TASKS_TRACE_RCU
> + tests[2].run = true;
> + call_rcu_tasks_trace(&tests[2].rh, test_rcu_tasks_callback);
> + synchronize_rcu_tasks_trace();
> +#endif
> + }
> +}
> +
> +static int rcu_tasks_verify_self_tests(void)
> +{
> + int ret, i;
Why not initialize "ret" in the declaration?
> +
> + for (i = 0, ret = 0; i < ARRAY_SIZE(tests); i++) {
> + if (tests[i].run) { // still hanging.
> + pr_err("%s has been failed.\n", tests[i].name);
> + ret = -1;
> + }
> + }
> +
> + if (ret)
> + WARN_ON(1);
> +
> + return ret;
> }
> +late_initcall(rcu_tasks_verify_self_tests);
>
> #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
> static inline void rcu_tasks_bootup_oddness(void) {}
> --
> 2.20.1
Again, much improved!
Thanx, Paul
