linux-kernel - [PATCH tip/core/rcu 10/17] rcu: Add ->dynticks field to rcu

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Date:   Fri,  1 Dec 2017 11:36:41 -0800
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 10/17] rcu: Add ->dynticks field to rcu_dyntick trace event

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 include/trace/events/rcu.h | 13 ++++++++-----
 kernel/rcu/tree.c          | 16 +++++++---------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index b0a48231ea0e..d103de9f8c10 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -436,24 +436,27 @@ TRACE_EVENT(rcu_fqs,
  */
 TRACE_EVENT(rcu_dyntick,
 
-	TP_PROTO(const char *polarity, long oldnesting, long newnesting),
+	TP_PROTO(const char *polarity, long oldnesting, long newnesting, atomic_t dynticks),
 
-	TP_ARGS(polarity, oldnesting, newnesting),
+	TP_ARGS(polarity, oldnesting, newnesting, dynticks),
 
 	TP_STRUCT__entry(
 		__field(const char *, polarity)
 		__field(long, oldnesting)
 		__field(long, newnesting)
+		__field(int, dynticks)
 	),
 
 	TP_fast_assign(
 		__entry->polarity = polarity;
 		__entry->oldnesting = oldnesting;
 		__entry->newnesting = newnesting;
+		__entry->dynticks = atomic_read(&dynticks);
 	),
 
-	TP_printk("%s %lx %lx", __entry->polarity,
-		  __entry->oldnesting, __entry->newnesting)
+	TP_printk("%s %lx %lx %#3x", __entry->polarity,
+		  __entry->oldnesting, __entry->newnesting,
+		  __entry->dynticks & 0xfff)
 );
 
 /*
@@ -801,7 +804,7 @@ TRACE_EVENT(rcu_barrier,
 					 grplo, grphi, gp_tasks) do { } \
 	while (0)
 #define trace_rcu_fqs(rcuname, gpnum, cpu, qsevent) do { } while (0)
-#define trace_rcu_dyntick(polarity, oldnesting, newnesting) do { } while (0)
+#define trace_rcu_dyntick(polarity, oldnesting, newnesting, dyntick) do { } while (0)
 #define trace_rcu_prep_idle(reason) do { } while (0)
 #define trace_rcu_callback(rcuname, rhp, qlen_lazy, qlen) do { } while (0)
 #define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen_lazy, qlen) \
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 92de3bacda07..5febb76809f6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -761,13 +761,13 @@ static void rcu_eqs_enter_common(bool user)
 	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
 	lockdep_assert_irqs_disabled();
-	trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
+	trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
 	if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 	    !user && !is_idle_task(current)) {
 		struct task_struct *idle __maybe_unused =
 			idle_task(smp_processor_id());
 
-		trace_rcu_dyntick(TPS("Error on entry: not idle task"), rdtp->dynticks_nesting, 0);
+		trace_rcu_dyntick(TPS("Error on entry: not idle task"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
 		rcu_ftrace_dump(DUMP_ORIG);
 		WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
 			  current->pid, current->comm,
@@ -880,15 +880,14 @@ void rcu_nmi_exit(void)
 	 * leave it in non-RCU-idle state.
 	 */
 	if (rdtp->dynticks_nmi_nesting != 1) {
-		trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting,
-				  rdtp->dynticks_nmi_nesting - 2);
+		trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks);
 		WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
 			   rdtp->dynticks_nmi_nesting - 2);
 		return;
 	}
 
 	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0);
+	trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks);
 	WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 	rcu_dynticks_eqs_enter();
 }
@@ -953,14 +952,13 @@ static void rcu_eqs_exit_common(long newval, int user)
 	rcu_dynticks_task_exit();
 	rcu_dynticks_eqs_exit();
 	rcu_cleanup_after_idle();
-	trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, newval);
+	trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, newval, rdtp->dynticks);
 	if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 	    !user && !is_idle_task(current)) {
 		struct task_struct *idle __maybe_unused =
 			idle_task(smp_processor_id());
 
-		trace_rcu_dyntick(TPS("Error on exit: not idle task"),
-				  rdtp->dynticks_nesting, newval);
+		trace_rcu_dyntick(TPS("Error on exit: not idle task"), rdtp->dynticks_nesting, newval, rdtp->dynticks);
 		rcu_ftrace_dump(DUMP_ORIG);
 		WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
 			  current->pid, current->comm,
@@ -1062,7 +1060,7 @@ void rcu_nmi_enter(void)
 	}
 	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
 			  rdtp->dynticks_nmi_nesting,
-			  rdtp->dynticks_nmi_nesting + incby);
+			  rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks);
 	WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
 		   rdtp->dynticks_nmi_nesting + incby);
 	barrier();
-- 
2.5.2