Re: [PATCH v2] rcutorture: Make rcutorture support print rcu-tasks gp state

From: Paul E. McKenney
Date: Sun Mar 17 2024 - 16:17:09 EST

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In reply to: Zqiang: "[PATCH v2] rcutorture: Make rcutorture support print rcu-tasks gp state"
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On Sun, Mar 17, 2024 at 07:38:11PM +0800, Zqiang wrote:
> This commit make rcu-tasks related rcutorture test support rcu-tasks
> gp state printing when the writer stall occurs or the at the end of
> rcutorture test, and generate rcu_ops->get_gp_data() operation to
> simplify the acquisition of gp state for different types of rcutorture
> tests.
>
> Signed-off-by: Zqiang <qiang.zhang1211@xxxxxxxxx>

Much better!!!

A few questions below. One small change left, a question on testing,
and the possibility of a few cleanup patches if you are interested.

Thanx, Paul

> ---
>
> [ 47.582683] rcu: Start-test grace-period state: g4313 f0x0
> [ 73.780444] rcu: End-test grace-period state: g15728 f0x0 total-gps=2854
>
> [ 99.013921] srcu: Start-test grace-period state: g0 f0x0
> [ 126.596727] srcu: End-test grace-period state: g10292 f0x0 total-gps=10292
>
> [ 175.664991] srcud: Start-test grace-period state: g0 f0x0
> [ 195.012774] srcud: End-test grace-period state: g7628 f0x0 total-gps=7628
>
> [ 216.943521] tasks: Start-test grace-period state: g8 f0x0
> [ 234.245093] tasks: End-test grace-period state: g300 f0x0 total-gps=292
>
> [ 267.139368] tasks-rude: Start-test grace-period state: g8 f0x0
> [ 296.132748] tasks-rude: End-test grace-period state: g684 f0x0 total-gps=676
>
> [ 316.044241] tasks-tracing: Start-test grace-period state: g8 f0x0
> [ 342.020447] tasks-tracing: End-test grace-period state: g348 f0x0 total-gps=340
>
> kernel/rcu/rcu.h | 20 ++++++++++----------
> kernel/rcu/rcutorture.c | 29 +++++++++++++++++++++--------
> kernel/rcu/srcutree.c | 5 +----
> kernel/rcu/tasks.h | 21 +++++++++++++++++++++
> kernel/rcu/tree.c | 13 +++----------
> 5 files changed, 56 insertions(+), 32 deletions(-)
>
> diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
> index 86fce206560e..38238e595a61 100644
> --- a/kernel/rcu/rcu.h
> +++ b/kernel/rcu/rcu.h
> @@ -522,12 +522,18 @@ static inline void show_rcu_tasks_gp_kthreads(void) {}
>
> #ifdef CONFIG_TASKS_RCU
> struct task_struct *get_rcu_tasks_gp_kthread(void);
> +void rcu_tasks_get_gp_data(int *flags, unsigned long *gp_seq);
> #endif // # ifdef CONFIG_TASKS_RCU
>
> #ifdef CONFIG_TASKS_RUDE_RCU
> struct task_struct *get_rcu_tasks_rude_gp_kthread(void);
> +void rcu_tasks_rude_get_gp_data(int *flags, unsigned long *gp_seq);
> #endif // # ifdef CONFIG_TASKS_RUDE_RCU
>
> +#ifdef CONFIG_TASKS_TRACE_RCU
> +void rcu_tasks_trace_get_gp_data(int *flags, unsigned long *gp_seq);
> +#endif
> +

If you have not already done so, could you please test with the rcutorture
scenarios, while artificially forcing that warning to trigger?

For example, CONFIG_TASKS_TRACE_RCU can be tested using this command
line:

tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 5m --configs "TRACE01 TRACE02" --trust-make

You can add more scenarios to the --configs argument, and the rest of
them can be found in tools/testing/selftests/rcutorture/configs/rcu.

> #ifdef CONFIG_TASKS_RCU_GENERIC
> void tasks_cblist_init_generic(void);
> #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
> @@ -557,8 +563,7 @@ static inline void rcu_set_jiffies_lazy_flush(unsigned long j) { }
> #endif
>
> #if defined(CONFIG_TREE_RCU)
> -void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
> - unsigned long *gp_seq);
> +void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq);
> void do_trace_rcu_torture_read(const char *rcutorturename,
> struct rcu_head *rhp,
> unsigned long secs,
> @@ -566,8 +571,7 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
> unsigned long c);
> void rcu_gp_set_torture_wait(int duration);
> #else
> -static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
> - int *flags, unsigned long *gp_seq)
> +static inline void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq)
> {
> *flags = 0;
> *gp_seq = 0;
> @@ -587,20 +591,16 @@ static inline void rcu_gp_set_torture_wait(int duration) { }
>
> #ifdef CONFIG_TINY_SRCU
>
> -static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
> - struct srcu_struct *sp, int *flags,
> +static inline void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
> unsigned long *gp_seq)
> {
> - if (test_type != SRCU_FLAVOR)
> - return;
> *flags = 0;
> *gp_seq = sp->srcu_idx;
> }
>
> #elif defined(CONFIG_TREE_SRCU)
>
> -void srcutorture_get_gp_data(enum rcutorture_type test_type,
> - struct srcu_struct *sp, int *flags,
> +void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
> unsigned long *gp_seq);
>
> #endif
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 2f43d31fb7a5..2e8a037072eb 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -381,6 +381,7 @@ struct rcu_torture_ops {
> void (*gp_kthread_dbg)(void);
> bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
> int (*stall_dur)(void);
> + void (*get_gp_data)(int *flags, unsigned long *gp_seq);
> long cbflood_max;
> int irq_capable;
> int can_boost;
> @@ -569,6 +570,7 @@ static struct rcu_torture_ops rcu_ops = {
> .gp_kthread_dbg = show_rcu_gp_kthreads,
> .check_boost_failed = rcu_check_boost_fail,
> .stall_dur = rcu_jiffies_till_stall_check,
> + .get_gp_data = rcutorture_get_gp_data,
> .irq_capable = 1,
> .can_boost = IS_ENABLED(CONFIG_RCU_BOOST),
> .extendables = RCUTORTURE_MAX_EXTEND,
> @@ -612,6 +614,7 @@ static struct rcu_torture_ops rcu_busted_ops = {
> .sync = synchronize_rcu_busted,
> .exp_sync = synchronize_rcu_busted,
> .call = call_rcu_busted,
> + .get_gp_data = NULL,

When this is NULL, please just leave it out.

If you wish, you can also send separate patches removing the pre-existing
initialization of function pointers to NULL, one per function pointer.

> .cb_barrier = NULL,
> .fqs = NULL,
> .stats = NULL,
> @@ -628,6 +631,11 @@ static struct srcu_struct srcu_ctld;
> static struct srcu_struct *srcu_ctlp = &srcu_ctl;
> static struct rcu_torture_ops srcud_ops;
>
> +static void srcu_get_gp_data(int *flags, unsigned long *gp_seq)
> +{
> + srcutorture_get_gp_data(srcu_ctlp, flags, gp_seq);
> +}
> +
> static int srcu_torture_read_lock(void)
> {
> if (cur_ops == &srcud_ops)
> @@ -736,6 +744,7 @@ static struct rcu_torture_ops srcu_ops = {
> .call = srcu_torture_call,
> .cb_barrier = srcu_torture_barrier,
> .stats = srcu_torture_stats,
> + .get_gp_data = srcu_get_gp_data,
> .cbflood_max = 50000,
> .irq_capable = 1,
> .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> @@ -774,6 +783,7 @@ static struct rcu_torture_ops srcud_ops = {
> .call = srcu_torture_call,
> .cb_barrier = srcu_torture_barrier,
> .stats = srcu_torture_stats,
> + .get_gp_data = srcu_get_gp_data,
> .cbflood_max = 50000,
> .irq_capable = 1,
> .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> @@ -796,6 +806,7 @@ static struct rcu_torture_ops busted_srcud_ops = {
> .call = srcu_torture_call,
> .cb_barrier = srcu_torture_barrier,
> .stats = srcu_torture_stats,
> + .get_gp_data = NULL,
> .irq_capable = 1,
> .no_pi_lock = IS_ENABLED(CONFIG_TINY_SRCU),
> .extendables = RCUTORTURE_MAX_EXTEND,
> @@ -838,6 +849,7 @@ static struct rcu_torture_ops trivial_ops = {
> .get_gp_seq = rcu_no_completed,
> .sync = synchronize_rcu_trivial,
> .exp_sync = synchronize_rcu_trivial,
> + .get_gp_data = NULL,
> .fqs = NULL,
> .stats = NULL,
> .irq_capable = 1,
> @@ -882,6 +894,7 @@ static struct rcu_torture_ops tasks_ops = {
> .call = call_rcu_tasks,
> .cb_barrier = rcu_barrier_tasks,
> .gp_kthread_dbg = show_rcu_tasks_classic_gp_kthread,
> + .get_gp_data = rcu_tasks_get_gp_data,
> .fqs = NULL,
> .stats = NULL,
> .irq_capable = 1,
> @@ -922,6 +935,7 @@ static struct rcu_torture_ops tasks_rude_ops = {
> .call = call_rcu_tasks_rude,
> .cb_barrier = rcu_barrier_tasks_rude,
> .gp_kthread_dbg = show_rcu_tasks_rude_gp_kthread,
> + .get_gp_data = rcu_tasks_rude_get_gp_data,
> .cbflood_max = 50000,
> .fqs = NULL,
> .stats = NULL,
> @@ -974,6 +988,7 @@ static struct rcu_torture_ops tasks_tracing_ops = {
> .call = call_rcu_tasks_trace,
> .cb_barrier = rcu_barrier_tasks_trace,
> .gp_kthread_dbg = show_rcu_tasks_trace_gp_kthread,
> + .get_gp_data = rcu_tasks_trace_get_gp_data,
> .cbflood_max = 50000,
> .fqs = NULL,
> .stats = NULL,
> @@ -2264,10 +2279,8 @@ rcu_torture_stats_print(void)
> int __maybe_unused flags = 0;
> unsigned long __maybe_unused gp_seq = 0;
>
> - rcutorture_get_gp_data(cur_ops->ttype,
> - &flags, &gp_seq);
> - srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
> - &flags, &gp_seq);
> + if (cur_ops->get_gp_data)
> + cur_ops->get_gp_data(&flags, &gp_seq);
> wtp = READ_ONCE(writer_task);
> pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
> rcu_torture_writer_state_getname(),
> @@ -3390,8 +3403,8 @@ rcu_torture_cleanup(void)
> fakewriter_tasks = NULL;
> }
>
> - rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
> - srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
> + if (cur_ops->get_gp_data)
> + cur_ops->get_gp_data(&flags, &gp_seq);
> pr_alert("%s: End-test grace-period state: g%ld f%#x total-gps=%ld\n",
> cur_ops->name, (long)gp_seq, flags,
> rcutorture_seq_diff(gp_seq, start_gp_seq));
> @@ -3762,8 +3775,8 @@ rcu_torture_init(void)
> nrealreaders = 1;
> }
> rcu_torture_print_module_parms(cur_ops, "Start of test");
> - rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
> - srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
> + if (cur_ops->get_gp_data)
> + cur_ops->get_gp_data(&flags, &gp_seq);
> start_gp_seq = gp_seq;
> pr_alert("%s: Start-test grace-period state: g%ld f%#x\n",
> cur_ops->name, (long)gp_seq, flags);
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index d19326486edd..98f79ba01b0a 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -1828,12 +1828,9 @@ static void process_srcu(struct work_struct *work)
> srcu_reschedule(ssp, curdelay);
> }
>
> -void srcutorture_get_gp_data(enum rcutorture_type test_type,
> - struct srcu_struct *ssp, int *flags,
> +void srcutorture_get_gp_data(struct srcu_struct *ssp, int *flags,
> unsigned long *gp_seq)
> {
> - if (test_type != SRCU_FLAVOR)
> - return;
> *flags = 0;
> *gp_seq = rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq);
> }
> diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> index e83adcdb49b5..e7ac9138a4fd 100644
> --- a/kernel/rcu/tasks.h
> +++ b/kernel/rcu/tasks.h
> @@ -1182,6 +1182,13 @@ struct task_struct *get_rcu_tasks_gp_kthread(void)
> }
> EXPORT_SYMBOL_GPL(get_rcu_tasks_gp_kthread);
>
> +void rcu_tasks_get_gp_data(int *flags, unsigned long *gp_seq)
> +{
> + *flags = 0;
> + *gp_seq = rcu_seq_current(&rcu_tasks.tasks_gp_seq);
> +}
> +EXPORT_SYMBOL_GPL(rcu_tasks_get_gp_data);
> +
> /*
> * Protect against tasklist scan blind spot while the task is exiting and
> * may be removed from the tasklist. Do this by adding the task to yet
> @@ -1361,6 +1368,13 @@ struct task_struct *get_rcu_tasks_rude_gp_kthread(void)
> }
> EXPORT_SYMBOL_GPL(get_rcu_tasks_rude_gp_kthread);
>
> +void rcu_tasks_rude_get_gp_data(int *flags, unsigned long *gp_seq)
> +{
> + *flags = 0;
> + *gp_seq = rcu_seq_current(&rcu_tasks_rude.tasks_gp_seq);
> +}
> +EXPORT_SYMBOL_GPL(rcu_tasks_rude_get_gp_data);
> +
> #endif /* #ifdef CONFIG_TASKS_RUDE_RCU */
>
> ////////////////////////////////////////////////////////////////////////
> @@ -2020,6 +2034,13 @@ struct task_struct *get_rcu_tasks_trace_gp_kthread(void)
> }
> EXPORT_SYMBOL_GPL(get_rcu_tasks_trace_gp_kthread);
>
> +void rcu_tasks_trace_get_gp_data(int *flags, unsigned long *gp_seq)
> +{
> + *flags = 0;
> + *gp_seq = rcu_seq_current(&rcu_tasks_trace.tasks_gp_seq);
> +}
> +EXPORT_SYMBOL_GPL(rcu_tasks_trace_get_gp_data);
> +
> #else /* #ifdef CONFIG_TASKS_TRACE_RCU */
> static void exit_tasks_rcu_finish_trace(struct task_struct *t) { }
> #endif /* #else #ifdef CONFIG_TASKS_TRACE_RCU */
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 9fbb5ab57c84..e229a12afe31 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -539,17 +539,10 @@ static struct rcu_node *rcu_get_root(void)
> /*
> * Send along grace-period-related data for rcutorture diagnostics.
> */
> -void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
> - unsigned long *gp_seq)
> +void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq)
> {
> - switch (test_type) {
> - case RCU_FLAVOR:
> - *flags = READ_ONCE(rcu_state.gp_flags);
> - *gp_seq = rcu_seq_current(&rcu_state.gp_seq);
> - break;
> - default:
> - break;
> - }
> + *flags = READ_ONCE(rcu_state.gp_flags);
> + *gp_seq = rcu_seq_current(&rcu_state.gp_seq);
> }
> EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
>
> --
> 2.17.1
>

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In reply to: Zqiang: "[PATCH v2] rcutorture: Make rcutorture support print rcu-tasks gp state"
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