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Message-Id: <20240816064921.57645-11-neeraj.upadhyay@kernel.org>
Date: Fri, 16 Aug 2024 12:19:20 +0530
From: neeraj.upadhyay@...nel.org
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
kernel-team@...a.com,
rostedt@...dmis.org,
paulmck@...nel.org,
neeraj.upadhyay@...nel.org,
neeraj.upadhyay@....com,
boqun.feng@...il.com,
joel@...lfernandes.org,
urezki@...il.com,
frederic@...nel.org
Subject: [PATCH rcu 11/12] rcu/tasks: Add detailed grace-period and barrier diagnostics
From: "Paul E. McKenney" <paulmck@...nel.org>
This commit adds rcu_tasks_torture_stats_print(),
rcu_tasks_trace_torture_stats_print(), and
rcu_tasks_rude_torture_stats_print() functions that provide detailed
diagnostics on grace-period, callback, and barrier state.
Signed-off-by: "Paul E. McKenney" <paulmck@...nel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@...nel.org>
---
include/linux/rcupdate.h | 3 ++
kernel/rcu/tasks.h | 66 ++++++++++++++++++++++++++++++++++++++--
2 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 31e679c7110e..17463e95b6ef 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -164,6 +164,7 @@ static inline void rcu_nocb_flush_deferred_wakeup(void) { }
} while (0)
void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);
void synchronize_rcu_tasks(void);
+void rcu_tasks_torture_stats_print(char *tt, char *tf);
# else
# define rcu_tasks_classic_qs(t, preempt) do { } while (0)
# define call_rcu_tasks call_rcu
@@ -190,6 +191,7 @@ void rcu_tasks_trace_qs_blkd(struct task_struct *t);
rcu_tasks_trace_qs_blkd(t); \
} \
} while (0)
+void rcu_tasks_trace_torture_stats_print(char *tt, char *tf);
# else
# define rcu_tasks_trace_qs(t) do { } while (0)
# endif
@@ -202,6 +204,7 @@ do { \
# ifdef CONFIG_TASKS_RUDE_RCU
void synchronize_rcu_tasks_rude(void);
+void rcu_tasks_rude_torture_stats_print(char *tt, char *tf);
# endif
#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t, false)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index d44abcd656d6..5f6d80ce1e47 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -714,9 +714,7 @@ static void __init rcu_tasks_bootup_oddness(void)
#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
}
-#endif /* #ifndef CONFIG_TINY_RCU */
-#ifndef CONFIG_TINY_RCU
/* Dump out rcutorture-relevant state common to all RCU-tasks flavors. */
static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s)
{
@@ -750,6 +748,52 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s)
rtp->lazy_jiffies,
s);
}
+
+/* Dump out more rcutorture-relevant state common to all RCU-tasks flavors. */
+static void rcu_tasks_torture_stats_print_generic(struct rcu_tasks *rtp, char *tt,
+ char *tf, char *tst)
+{
+ cpumask_var_t cm;
+ int cpu;
+ bool gotcb = false;
+ unsigned long j = jiffies;
+
+ pr_alert("%s%s Tasks%s RCU g%ld gp_start %lu gp_jiffies %lu gp_state %d (%s).\n",
+ tt, tf, tst, data_race(rtp->tasks_gp_seq),
+ j - data_race(rtp->gp_start), j - data_race(rtp->gp_jiffies),
+ data_race(rtp->gp_state), tasks_gp_state_getname(rtp));
+ pr_alert("\tEnqueue shift %d limit %d Dequeue limit %d gpseq %lu.\n",
+ data_race(rtp->percpu_enqueue_shift),
+ data_race(rtp->percpu_enqueue_lim),
+ data_race(rtp->percpu_dequeue_lim),
+ data_race(rtp->percpu_dequeue_gpseq));
+ (void)zalloc_cpumask_var(&cm, GFP_KERNEL);
+ pr_alert("\tCallback counts:");
+ for_each_possible_cpu(cpu) {
+ long n;
+ struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
+
+ if (cpumask_available(cm) && !rcu_barrier_cb_is_done(&rtpcp->barrier_q_head))
+ cpumask_set_cpu(cpu, cm);
+ n = rcu_segcblist_n_cbs(&rtpcp->cblist);
+ if (!n)
+ continue;
+ pr_cont(" %d:%ld", cpu, n);
+ gotcb = true;
+ }
+ if (gotcb)
+ pr_cont(".\n");
+ else
+ pr_cont(" (none).\n");
+ pr_alert("\tBarrier seq %lu count %d holdout CPUs ",
+ data_race(rtp->barrier_q_seq), atomic_read(&rtp->barrier_q_count));
+ if (cpumask_available(cm) && !cpumask_empty(cm))
+ pr_cont(" %*pbl.\n", cpumask_pr_args(cm));
+ else
+ pr_cont("(none).\n");
+ free_cpumask_var(cm);
+}
+
#endif // #ifndef CONFIG_TINY_RCU
static void exit_tasks_rcu_finish_trace(struct task_struct *t);
@@ -1201,6 +1245,12 @@ void show_rcu_tasks_classic_gp_kthread(void)
show_rcu_tasks_generic_gp_kthread(&rcu_tasks, "");
}
EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread);
+
+void rcu_tasks_torture_stats_print(char *tt, char *tf)
+{
+ rcu_tasks_torture_stats_print_generic(&rcu_tasks, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_torture_stats_print);
#endif // !defined(CONFIG_TINY_RCU)
struct task_struct *get_rcu_tasks_gp_kthread(void)
@@ -1361,6 +1411,12 @@ void show_rcu_tasks_rude_gp_kthread(void)
show_rcu_tasks_generic_gp_kthread(&rcu_tasks_rude, "");
}
EXPORT_SYMBOL_GPL(show_rcu_tasks_rude_gp_kthread);
+
+void rcu_tasks_rude_torture_stats_print(char *tt, char *tf)
+{
+ rcu_tasks_torture_stats_print_generic(&rcu_tasks_rude, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_rude_torture_stats_print);
#endif // !defined(CONFIG_TINY_RCU)
struct task_struct *get_rcu_tasks_rude_gp_kthread(void)
@@ -2038,6 +2094,12 @@ void show_rcu_tasks_trace_gp_kthread(void)
show_rcu_tasks_generic_gp_kthread(&rcu_tasks_trace, buf);
}
EXPORT_SYMBOL_GPL(show_rcu_tasks_trace_gp_kthread);
+
+void rcu_tasks_trace_torture_stats_print(char *tt, char *tf)
+{
+ rcu_tasks_torture_stats_print_generic(&rcu_tasks_trace, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_trace_torture_stats_print);
#endif // !defined(CONFIG_TINY_RCU)
struct task_struct *get_rcu_tasks_trace_gp_kthread(void)
--
2.40.1
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