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[PATCH tip/core/rcu 07/16] rcu: Add expedited-grace-period event tracing

From "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject [PATCH tip/core/rcu 07/16] rcu: Add expedited-grace-period event tracing
Date 2016-04-12 17:30 +0200
Message-ID <rn8qm-16v-9@gated-at.bofh.it> (permalink)
References <rn8qm-16v-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c        | 20 +++++++++++++-------
 kernel/rcu/tree_plugin.h |  3 +++
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 79e9206a7b11..524026fd9dd7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3584,17 +3584,18 @@ static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp,
 			       atomic_long_t *stat, unsigned long s)
 {
 	if (rcu_exp_gp_seq_done(rsp, s)) {
+		trace_rcu_exp_grace_period(rsp->name, s, TPS("done"));
 		if (rnp) {
-			mutex_unlock(&rnp->exp_funnel_mutex);
 			trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
 						  rnp->grplo, rnp->grphi,
 						  TPS("rel"));
+			mutex_unlock(&rnp->exp_funnel_mutex);
 		} else if (rdp) {
-			mutex_unlock(&rdp->exp_funnel_mutex);
 			trace_rcu_exp_funnel_lock(rsp->name,
 						  rdp->mynode->level + 1,
 						  rdp->cpu, rdp->cpu,
 						  TPS("rel"));
+			mutex_unlock(&rdp->exp_funnel_mutex);
 		}
 		/* Ensure test happens before caller kfree(). */
 		smp_mb__before_atomic(); /* ^^^ */
@@ -3624,12 +3625,12 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
 	rnp0 = rcu_get_root(rsp);
 	if (!mutex_is_locked(&rnp0->exp_funnel_mutex)) {
 		if (mutex_trylock(&rnp0->exp_funnel_mutex)) {
-			if (sync_exp_work_done(rsp, rnp0, NULL,
-					       &rdp->expedited_workdone0, s))
-				return NULL;
 			trace_rcu_exp_funnel_lock(rsp->name, rnp0->level,
 						  rnp0->grplo, rnp0->grphi,
 						  TPS("acq"));
+			if (sync_exp_work_done(rsp, rnp0, NULL,
+					       &rdp->expedited_workdone0, s))
+				return NULL;
 			return rnp0;
 		}
 	}
@@ -3656,16 +3657,16 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
 		trace_rcu_exp_funnel_lock(rsp->name, rnp0->level,
 					  rnp0->grplo, rnp0->grphi, TPS("acq"));
 		if (rnp1) {
-			mutex_unlock(&rnp1->exp_funnel_mutex);
 			trace_rcu_exp_funnel_lock(rsp->name, rnp1->level,
 						  rnp1->grplo, rnp1->grphi,
 						  TPS("rel"));
+			mutex_unlock(&rnp1->exp_funnel_mutex);
 		} else {
-			mutex_unlock(&rdp->exp_funnel_mutex);
 			trace_rcu_exp_funnel_lock(rsp->name,
 						  rdp->mynode->level + 1,
 						  rdp->cpu, rdp->cpu,
 						  TPS("rel"));
+			mutex_unlock(&rdp->exp_funnel_mutex);
 		}
 		rnp1 = rnp0;
 	}
@@ -3895,16 +3896,21 @@ void synchronize_sched_expedited(void)
 
 	/* Take a snapshot of the sequence number.  */
 	s = rcu_exp_gp_seq_snap(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
 
 	rnp = exp_funnel_lock(rsp, s);
 	if (rnp == NULL)
 		return;  /* Someone else did our work for us. */
 
 	rcu_exp_gp_seq_start(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));
 	sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
 	synchronize_sched_expedited_wait(rsp);
 
 	rcu_exp_gp_seq_end(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
+	trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
+				  rnp->grplo, rnp->grphi, TPS("rel"));
 	mutex_unlock(&rnp->exp_funnel_mutex);
 }
 EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index cd2dae43ff48..36e94aed38a7 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -750,12 +750,14 @@ void synchronize_rcu_expedited(void)
 	}
 
 	s = rcu_exp_gp_seq_snap(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
 
 	rnp_unlock = exp_funnel_lock(rsp, s);
 	if (rnp_unlock == NULL)
 		return;  /* Someone else did our work for us. */
 
 	rcu_exp_gp_seq_start(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));
 
 	/* Initialize the rcu_node tree in preparation for the wait. */
 	sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
@@ -766,6 +768,7 @@ void synchronize_rcu_expedited(void)
 
 	/* Clean up and exit. */
 	rcu_exp_gp_seq_end(rsp);
+	trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
 	mutex_unlock(&rnp_unlock->exp_funnel_mutex);
 	trace_rcu_exp_funnel_lock(rsp->name, rnp_unlock->level,
 				  rnp_unlock->grplo, rnp_unlock->grphi,
-- 
2.5.2

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[PATCH tip/core/rcu 0/16] Expedited grace-period changes for 4.7 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:30 +0200
  [PATCH tip/core/rcu 07/16] rcu: Add expedited-grace-period event tracing "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:30 +0200
  [PATCH tip/core/rcu 02/16] rcu: Make expedited RCU-preempt stall warnings count accurately "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:30 +0200
  [PATCH tip/core/rcu 10/16] rcu: Shorten expedited_workdone* to exp_workdone* "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:30 +0200
  [PATCH tip/core/rcu 09/16] rcu: Force boolean subscript for expedited stall warnings "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:30 +0200
  [PATCH tip/core/rcu 08/16] rcu: Remove expedited GP funnel-lock bypass "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 05/16] rcu: Add event tracing definitions for expedited grace periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 03/16] rcu: Make cond_resched_rcu_qs() supply RCU-sched expedited QS "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 06/16] rcu: Add funnel-locking tracing for expedited grace periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 14/16] rcu: Consolidate expedited GP tracing into rcu_exp_gp_seq_snap() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 01/16] rcu: Make expedited RCU-sched grace period immediately detect idle "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 15/16] rcu: Consolidate expedited GP code into exp_funnel_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 16/16] rcu: Overlap wakeups with next expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 12/16] rcu: Add exp_funnel_lock() fastpath "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 11/16] rcu: Enforce expedited-GP fairness via funnel wait queue "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 04/16] rcu: Fix synchronize_rcu_expedited() header comment "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200
  [PATCH tip/core/rcu 13/16] rcu: Consolidate expedited GP code into rcu_exp_wait_wake() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:40 +0200

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