linux-kernel - [PATCH tip/core/rcu 05/10] rcu: Remove "cpu" argument to rcu_preempt_check

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Date:	Tue, 28 Oct 2014 14:53:32 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...nel.org, laijs@...fujitsu.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 05/10] rcu: Remove "cpu" argument to rcu_preempt_check_callbacks()

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

Because rcu_preempt_check_callbacks()'s argument is guaranteed to
always be the current CPU, drop the argument and replace per_cpu()
with __this_cpu_read().

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree.c        | 2 +-
 kernel/rcu/tree.h        | 2 +-
 kernel/rcu/tree_plugin.h | 8 ++++----
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0670ba3a65d3..1af5e2cdcbeb 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2420,7 +2420,7 @@ void rcu_check_callbacks(int user)
 
 		rcu_bh_qs();
 	}
-	rcu_preempt_check_callbacks(smp_processor_id());
+	rcu_preempt_check_callbacks();
 	if (rcu_pending())
 		invoke_rcu_core();
 	if (user)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 8e90562010ec..94a26e330c1b 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -561,7 +561,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
 				     struct rcu_node *rnp,
 				     struct rcu_data *rdp);
 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
-static void rcu_preempt_check_callbacks(int cpu);
+static void rcu_preempt_check_callbacks(void);
 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 09547143628a..7158814b7b4a 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -621,7 +621,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
  *
  * Caller must disable hard irqs.
  */
-static void rcu_preempt_check_callbacks(int cpu)
+static void rcu_preempt_check_callbacks(void)
 {
 	struct task_struct *t = current;
 
@@ -630,8 +630,8 @@ static void rcu_preempt_check_callbacks(int cpu)
 		return;
 	}
 	if (t->rcu_read_lock_nesting > 0 &&
-	    per_cpu(rcu_preempt_data, cpu).qs_pending &&
-	    !per_cpu(rcu_preempt_data, cpu).passed_quiesce)
+	    __this_cpu_read(rcu_preempt_data.qs_pending) &&
+	    !__this_cpu_read(rcu_preempt_data.passed_quiesce))
 		t->rcu_read_unlock_special.b.need_qs = true;
 }
 
@@ -1017,7 +1017,7 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
  * Because preemptible RCU does not exist, it never has any callbacks
  * to check.
  */
-static void rcu_preempt_check_callbacks(int cpu)
+static void rcu_preempt_check_callbacks(void)
 {
 }
 
-- 
1.8.1.5

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