linux-kernel - [PATCH tip/core/rcu 14/22] rcu: Remove unneeded __rcu_process

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Date:	Fri, 22 Jun 2012 08:17:13 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu, patches@...aro.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 14/22] rcu: Remove unneeded __rcu_process_callbacks() argument

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

With the advent of __this_cpu_ptr(), it is no longer necessary to pass
both the rcu_state and rcu_data structures into __rcu_process_callbacks().
This commit therefore computes the rcu_data pointer from the rcu_state
pointer within __rcu_process_callbacks() so that callers can pass in
only the pointer to the rcu_state structure.  This paves the way for
linking the rcu_state structures together and iterating over them.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@...htriplett.org>
---
 kernel/rcutree.c        |    8 ++++----
 kernel/rcutree_plugin.h |    3 +--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 5c1c6ae..cf7c373 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1785,9 +1785,10 @@ unlock_fqs_ret:
  * whom the rdp belongs.
  */
 static void
-__rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
+__rcu_process_callbacks(struct rcu_state *rsp)
 {
 	unsigned long flags;
+	struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
 
 	WARN_ON_ONCE(rdp->beenonline == 0);
 
@@ -1824,9 +1825,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
 static void rcu_process_callbacks(struct softirq_action *unused)
 {
 	trace_rcu_utilization("Start RCU core");
-	__rcu_process_callbacks(&rcu_sched_state,
-				&__get_cpu_var(rcu_sched_data));
-	__rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
+	__rcu_process_callbacks(&rcu_sched_state);
+	__rcu_process_callbacks(&rcu_bh_state);
 	rcu_preempt_process_callbacks();
 	trace_rcu_utilization("End RCU core");
 }
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index a401508..c6e986c 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -687,8 +687,7 @@ static void rcu_preempt_check_callbacks(int cpu)
  */
 static void rcu_preempt_process_callbacks(void)
 {
-	__rcu_process_callbacks(&rcu_preempt_state,
-				&__get_cpu_var(rcu_preempt_data));
+	__rcu_process_callbacks(&rcu_preempt_state);
 }
 
 #ifdef CONFIG_RCU_BOOST
-- 
1.7.8

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