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From:   "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To:     linux-kernel@vger.kernel.org
Cc:     mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
        akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
        josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
        rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
        fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 31/52] rcu: Remove rsp parameter from _rcu_barrier() and friends
Date:   Wed, 29 Aug 2018 15:38:33 -0700
In-Reply-To: <20180829223830.GA1800@linux.vnet.ibm.com>
References: <20180829223830.GA1800@linux.vnet.ibm.com>
Message-Id: <20180829223854.4055-31-paulmck@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

There now is only one rcu_state structure in a given build of the
Linux kernel, so there is no need to pass it as a parameter to RCU's
functions.  This commit therefore removes the rsp parameter from
_rcu_barrier_trace() and _rcu_barrier().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e347a6b2984c..8028936dc95d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3155,11 +3155,10 @@ static bool rcu_cpu_has_callbacks(bool *all_lazy)
  * Helper function for _rcu_barrier() tracing.  If tracing is disabled,
  * the compiler is expected to optimize this away.
  */
-static void _rcu_barrier_trace(struct rcu_state *rsp, const char *s,
-			       int cpu, unsigned long done)
+static void _rcu_barrier_trace(const char *s, int cpu, unsigned long done)
 {
-	trace_rcu_barrier(rsp->name, s, cpu,
-			  atomic_read(&rsp->barrier_cpu_count), done);
+	trace_rcu_barrier(rcu_state.name, s, cpu,
+			  atomic_read(&rcu_state.barrier_cpu_count), done);
 }
 
 /*
@@ -3172,11 +3171,10 @@ static void rcu_barrier_callback(struct rcu_head *rhp)
 	struct rcu_state *rsp = rdp->rsp;
 
 	if (atomic_dec_and_test(&rsp->barrier_cpu_count)) {
-		_rcu_barrier_trace(rsp, TPS("LastCB"), -1,
-				   rsp->barrier_sequence);
+		_rcu_barrier_trace(TPS("LastCB"), -1, rsp->barrier_sequence);
 		complete(&rsp->barrier_completion);
 	} else {
-		_rcu_barrier_trace(rsp, TPS("CB"), -1, rsp->barrier_sequence);
+		_rcu_barrier_trace(TPS("CB"), -1, rsp->barrier_sequence);
 	}
 }
 
@@ -3188,15 +3186,14 @@ static void rcu_barrier_func(void *type)
 	struct rcu_state *rsp = type;
 	struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
 
-	_rcu_barrier_trace(rsp, TPS("IRQ"), -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(TPS("IRQ"), -1, rsp->barrier_sequence);
 	rdp->barrier_head.func = rcu_barrier_callback;
 	debug_rcu_head_queue(&rdp->barrier_head);
 	if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) {
 		atomic_inc(&rsp->barrier_cpu_count);
 	} else {
 		debug_rcu_head_unqueue(&rdp->barrier_head);
-		_rcu_barrier_trace(rsp, TPS("IRQNQ"), -1,
-				   rsp->barrier_sequence);
+		_rcu_barrier_trace(TPS("IRQNQ"), -1, rsp->barrier_sequence);
 	}
 }
 
@@ -3204,21 +3201,21 @@ static void rcu_barrier_func(void *type)
  * Orchestrate the specified type of RCU barrier, waiting for all
  * RCU callbacks of the specified type to complete.
  */
-static void _rcu_barrier(struct rcu_state *rsp)
+static void _rcu_barrier(void)
 {
 	int cpu;
 	struct rcu_data *rdp;
+	struct rcu_state *rsp = &rcu_state;
 	unsigned long s = rcu_seq_snap(&rsp->barrier_sequence);
 
-	_rcu_barrier_trace(rsp, TPS("Begin"), -1, s);
+	_rcu_barrier_trace(TPS("Begin"), -1, s);
 
 	/* Take mutex to serialize concurrent rcu_barrier() requests. */
 	mutex_lock(&rsp->barrier_mutex);
 
 	/* Did someone else do our work for us? */
 	if (rcu_seq_done(&rsp->barrier_sequence, s)) {
-		_rcu_barrier_trace(rsp, TPS("EarlyExit"), -1,
-				   rsp->barrier_sequence);
+		_rcu_barrier_trace(TPS("EarlyExit"), -1, rsp->barrier_sequence);
 		smp_mb(); /* caller's subsequent code after above check. */
 		mutex_unlock(&rsp->barrier_mutex);
 		return;
@@ -3226,7 +3223,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
 
 	/* Mark the start of the barrier operation. */
 	rcu_seq_start(&rsp->barrier_sequence);
-	_rcu_barrier_trace(rsp, TPS("Inc1"), -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(TPS("Inc1"), -1, rsp->barrier_sequence);
 
 	/*
 	 * Initialize the count to one rather than to zero in order to
@@ -3249,10 +3246,10 @@ static void _rcu_barrier(struct rcu_state *rsp)
 		rdp = per_cpu_ptr(&rcu_data, cpu);
 		if (rcu_is_nocb_cpu(cpu)) {
 			if (!rcu_nocb_cpu_needs_barrier(rsp, cpu)) {
-				_rcu_barrier_trace(rsp, TPS("OfflineNoCB"), cpu,
+				_rcu_barrier_trace(TPS("OfflineNoCB"), cpu,
 						   rsp->barrier_sequence);
 			} else {
-				_rcu_barrier_trace(rsp, TPS("OnlineNoCB"), cpu,
+				_rcu_barrier_trace(TPS("OnlineNoCB"), cpu,
 						   rsp->barrier_sequence);
 				smp_mb__before_atomic();
 				atomic_inc(&rsp->barrier_cpu_count);
@@ -3260,11 +3257,11 @@ static void _rcu_barrier(struct rcu_state *rsp)
 					   rcu_barrier_callback, cpu, 0);
 			}
 		} else if (rcu_segcblist_n_cbs(&rdp->cblist)) {
-			_rcu_barrier_trace(rsp, TPS("OnlineQ"), cpu,
+			_rcu_barrier_trace(TPS("OnlineQ"), cpu,
 					   rsp->barrier_sequence);
 			smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
 		} else {
-			_rcu_barrier_trace(rsp, TPS("OnlineNQ"), cpu,
+			_rcu_barrier_trace(TPS("OnlineNQ"), cpu,
 					   rsp->barrier_sequence);
 		}
 	}
@@ -3281,7 +3278,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
 	wait_for_completion(&rsp->barrier_completion);
 
 	/* Mark the end of the barrier operation. */
-	_rcu_barrier_trace(rsp, TPS("Inc2"), -1, rsp->barrier_sequence);
+	_rcu_barrier_trace(TPS("Inc2"), -1, rsp->barrier_sequence);
 	rcu_seq_end(&rsp->barrier_sequence);
 
 	/* Other rcu_barrier() invocations can now safely proceed. */
@@ -3293,7 +3290,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
  */
 void rcu_barrier_bh(void)
 {
-	_rcu_barrier(&rcu_state);
+	_rcu_barrier();
 }
 EXPORT_SYMBOL_GPL(rcu_barrier_bh);
 
@@ -3307,7 +3304,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier_bh);
  */
 void rcu_barrier(void)
 {
-	_rcu_barrier(&rcu_state);
+	_rcu_barrier();
 }
 EXPORT_SYMBOL_GPL(rcu_barrier);
 
-- 
2.17.1