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Date:	Tue,  6 Oct 2015 09:29:29 -0700
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,
	dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
	bobby.prani@...il.com,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 10/18] rcu: Stop silencing lockdep false positive for expedited grace periods

This reverts commit af859beaaba4 (rcu: Silence lockdep false positive
for expedited grace periods).  Because synchronize_rcu_expedited()
no longer invokes synchronize_sched_expedited(), ->exp_funnel_mutex
acquisition is no longer nested, so the false positive no longer happens.
This commit therefore removes the extra lockdep data structures, as they
are no longer needed.
---
 kernel/rcu/tree.c | 17 ++---------------
 kernel/rcu/tree.h |  8 --------
 2 files changed, 2 insertions(+), 23 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 869e58b92c53..57b83f6d5263 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -71,7 +71,6 @@ MODULE_ALIAS("rcutree");
 static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
 static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
 static struct lock_class_key rcu_exp_class[RCU_NUM_LVLS];
-static struct lock_class_key rcu_exp_sched_class[RCU_NUM_LVLS];
 
 /*
  * In order to export the rcu_state name to the tracing tools, it
@@ -4095,7 +4094,6 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
 static void __init
 rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 {
-	static struct lock_class_key rcu_exp_sched_rdp_class;
 	unsigned long flags;
 	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_node *rnp = rcu_get_root(rsp);
@@ -4111,10 +4109,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 	mutex_init(&rdp->exp_funnel_mutex);
 	rcu_boot_init_nocb_percpu_data(rdp);
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	if (rsp == &rcu_sched_state)
-		lockdep_set_class_and_name(&rdp->exp_funnel_mutex,
-					   &rcu_exp_sched_rdp_class,
-					   "rcu_data_exp_sched");
 }
 
 /*
@@ -4340,7 +4334,6 @@ static void __init rcu_init_one(struct rcu_state *rsp,
 	static const char * const buf[] = RCU_NODE_NAME_INIT;
 	static const char * const fqs[] = RCU_FQS_NAME_INIT;
 	static const char * const exp[] = RCU_EXP_NAME_INIT;
-	static const char * const exp_sched[] = RCU_EXP_SCHED_NAME_INIT;
 	static u8 fl_mask = 0x1;
 
 	int levelcnt[RCU_NUM_LVLS];		/* # nodes in each level. */
@@ -4400,14 +4393,8 @@ static void __init rcu_init_one(struct rcu_state *rsp,
 			INIT_LIST_HEAD(&rnp->blkd_tasks);
 			rcu_init_one_nocb(rnp);
 			mutex_init(&rnp->exp_funnel_mutex);
-			if (rsp == &rcu_sched_state)
-				lockdep_set_class_and_name(
-					&rnp->exp_funnel_mutex,
-					&rcu_exp_sched_class[i], exp_sched[i]);
-			else
-				lockdep_set_class_and_name(
-					&rnp->exp_funnel_mutex,
-					&rcu_exp_class[i], exp[i]);
+			lockdep_set_class_and_name(&rnp->exp_funnel_mutex,
+						   &rcu_exp_class[i], exp[i]);
 		}
 	}
 
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 1b969cef8fe4..6f3b63b68886 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -70,8 +70,6 @@
 #  define RCU_NODE_NAME_INIT  { "rcu_node_0" }
 #  define RCU_FQS_NAME_INIT   { "rcu_node_fqs_0" }
 #  define RCU_EXP_NAME_INIT   { "rcu_node_exp_0" }
-#  define RCU_EXP_SCHED_NAME_INIT \
-			      { "rcu_node_exp_sched_0" }
 #elif NR_CPUS <= RCU_FANOUT_2
 #  define RCU_NUM_LVLS	      2
 #  define NUM_RCU_LVL_0	      1
@@ -81,8 +79,6 @@
 #  define RCU_NODE_NAME_INIT  { "rcu_node_0", "rcu_node_1" }
 #  define RCU_FQS_NAME_INIT   { "rcu_node_fqs_0", "rcu_node_fqs_1" }
 #  define RCU_EXP_NAME_INIT   { "rcu_node_exp_0", "rcu_node_exp_1" }
-#  define RCU_EXP_SCHED_NAME_INIT \
-			      { "rcu_node_exp_sched_0", "rcu_node_exp_sched_1" }
 #elif NR_CPUS <= RCU_FANOUT_3
 #  define RCU_NUM_LVLS	      3
 #  define NUM_RCU_LVL_0	      1
@@ -93,8 +89,6 @@
 #  define RCU_NODE_NAME_INIT  { "rcu_node_0", "rcu_node_1", "rcu_node_2" }
 #  define RCU_FQS_NAME_INIT   { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2" }
 #  define RCU_EXP_NAME_INIT   { "rcu_node_exp_0", "rcu_node_exp_1", "rcu_node_exp_2" }
-#  define RCU_EXP_SCHED_NAME_INIT \
-			      { "rcu_node_exp_sched_0", "rcu_node_exp_sched_1", "rcu_node_exp_sched_2" }
 #elif NR_CPUS <= RCU_FANOUT_4
 #  define RCU_NUM_LVLS	      4
 #  define NUM_RCU_LVL_0	      1
@@ -106,8 +100,6 @@
 #  define RCU_NODE_NAME_INIT  { "rcu_node_0", "rcu_node_1", "rcu_node_2", "rcu_node_3" }
 #  define RCU_FQS_NAME_INIT   { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2", "rcu_node_fqs_3" }
 #  define RCU_EXP_NAME_INIT   { "rcu_node_exp_0", "rcu_node_exp_1", "rcu_node_exp_2", "rcu_node_exp_3" }
-#  define RCU_EXP_SCHED_NAME_INIT \
-			      { "rcu_node_exp_sched_0", "rcu_node_exp_sched_1", "rcu_node_exp_sched_2", "rcu_node_exp_sched_3" }
 #else
 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
-- 
2.5.2

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