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[94.245.46.61]) by smtp.gmail.com with ESMTPSA id f15sm2135704lfc.10.2020.12.21.07.38.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Dec 2020 07:38:11 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 21 Dec 2020 16:38:09 +0100 To: "Paul E. McKenney" Cc: Uladzislau Rezki , LKML , RCU , Michael Ellerman , Andrew Morton , Daniel Axtens , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Peter Zijlstra , Michal Hocko , Thomas Gleixner , "Theodore Y . Ts'o" , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [PATCH 2/2] rcu-tasks: add RCU-tasks self tests Message-ID: <20201221153809.GA24756@pc638.lan> References: <20201209202732.5896-1-urezki@gmail.com> <20201209202732.5896-2-urezki@gmail.com> <20201216154959.GA2408@pc638.lan> <20201216232955.GO2657@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201216232955.GO2657@paulmck-ThinkPad-P72> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 16, 2020 at 03:29:55PM -0800, Paul E. McKenney wrote: > 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) > > > --- > > > 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)" > > 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) > > 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! > See below the v3 version. I hope i fixed all comments :) >From 06f7adfd84cbb1994d0e2693ee9dcdfd272a9bd0 Mon Sep 17 00:00:00 2001 From: "Uladzislau Rezki (Sony)" Date: Wed, 9 Dec 2020 21:27:32 +0100 Subject: [PATCH v3 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) --- kernel/rcu/tasks.h | 75 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 36607551f966..670212ed9648 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1224,6 +1224,43 @@ void show_rcu_tasks_gp_kthreads(void) } #endif /* #ifndef CONFIG_TINY_RCU */ +struct rcu_tasks_test_desc { + struct rcu_head rh; + const char *name; + bool notrun; +}; + +static struct rcu_tasks_test_desc tests[] = { + { + .name = "call_rcu_tasks()", + /* If not defined, the test is skipped. */ + .notrun = !IS_ENABLED(CONFIG_TASKS_RCU), + }, + { + .name = "call_rcu_tasks_rude()", + /* If not defined, the test is skipped. */ + .notrun = !IS_ENABLED(CONFIG_TASKS_RUDE_RCU), + }, + { + .name = "call_rcu_tasks_trace()", + /* If not defined, the test is skipped. */ + .notrun = !IS_ENABLED(CONFIG_TASKS_TRACE_RCU) + } +}; + +static int rcu_executed_test_counter; + +static void test_rcu_tasks_callback(struct rcu_head *rhp) +{ + struct rcu_tasks_test_desc *rttd = + container_of(rhp, struct rcu_tasks_test_desc, rh); + + pr_info("RCU-tasks test callback executed %d\n", + ++rcu_executed_test_counter); + + rttd->notrun = true; +} + void __init rcu_init_tasks_generic(void) { #ifdef CONFIG_TASKS_RCU @@ -1237,7 +1274,45 @@ 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 + synchronize_rcu_tasks(); + call_rcu_tasks(&tests[0].rh, test_rcu_tasks_callback); +#endif + +#ifdef CONFIG_TASKS_RUDE_RCU + synchronize_rcu_tasks_rude(); + call_rcu_tasks_rude(&tests[1].rh, test_rcu_tasks_callback); +#endif + +#ifdef CONFIG_TASKS_TRACE_RCU + synchronize_rcu_tasks_trace(); + call_rcu_tasks_trace(&tests[2].rh, test_rcu_tasks_callback); +#endif + } +} + +static int rcu_tasks_verify_self_tests(void) +{ + int ret = 0; + int i; + + for (i = 0; i < ARRAY_SIZE(tests); i++) { + if (!tests[i].notrun) { // 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 -- Vlad Rezki