linux-kernel - [PATCH tip/core/rcu 4/8] rcu: Switch callers from rcu_process_gp_end() to note_gp

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Date:	Fri, 12 Apr 2013 16:32:33 -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, edumazet@...gle.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 4/8] rcu: Switch callers from rcu_process_gp_end() to note_gp_changes()

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

Because note_gp_changes() now incorporates rcu_process_gp_end() function,
this commit switches to the former and eliminates the latter.  In
addition, this commit changes external calls from __rcu_process_gp_end()
to __note_gp_changes().

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcutree.c        | 31 +++----------------------------
 kernel/rcutree_plugin.h |  2 +-
 2 files changed, 4 insertions(+), 29 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index dded193..9040e0f 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1334,28 +1334,6 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
 }
 
 /*
- * Advance this CPU's callbacks, but only if the current grace period
- * has ended.  This may be called only from the CPU to whom the rdp
- * belongs.
- */
-static void
-rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	unsigned long flags;
-	struct rcu_node *rnp;
-
-	local_irq_save(flags);
-	rnp = rdp->mynode;
-	if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */
-	    !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
-		local_irq_restore(flags);
-		return;
-	}
-	__rcu_process_gp_end(rsp, rnp, rdp);
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-}
-
-/*
  * Did someone else start a new RCU grace period start since we last
  * checked?  Update local state appropriately if so.  Must be called
  * on the CPU corresponding to rdp.
@@ -1383,9 +1361,6 @@ check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
 static void
 rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
 {
-	/* Prior grace period ended, so advance callbacks for current CPU. */
-	__rcu_process_gp_end(rsp, rnp, rdp);
-
 	/* Set state so that this CPU will detect the next quiescent state. */
 	__note_gp_changes(rsp, rnp, rdp);
 }
@@ -1521,7 +1496,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
 		ACCESS_ONCE(rnp->completed) = rsp->gpnum;
 		rdp = this_cpu_ptr(rsp->rda);
 		if (rnp == rdp->mynode)
-			__rcu_process_gp_end(rsp, rnp, rdp);
+			__note_gp_changes(rsp, rnp, rdp);
 		nocb += rcu_future_gp_cleanup(rsp, rnp);
 		raw_spin_unlock_irq(&rnp->lock);
 		cond_resched();
@@ -2254,7 +2229,7 @@ __rcu_process_callbacks(struct rcu_state *rsp)
 	WARN_ON_ONCE(rdp->beenonline == 0);
 
 	/* Handle the end of a grace period that some other CPU ended.  */
-	rcu_process_gp_end(rsp, rdp);
+	note_gp_changes(rsp, rdp);
 
 	/* Update RCU state based on any recent quiescent states. */
 	rcu_check_quiescent_state(rsp, rdp);
@@ -2340,7 +2315,7 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
 	if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) {
 
 		/* Are we ignoring a completed grace period? */
-		rcu_process_gp_end(rsp, rdp);
+		note_gp_changes(rsp, rdp);
 		check_for_new_grace_period(rsp, rdp);
 
 		/* Start a new grace period if one not already started. */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index e6cf7e5..69af628 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1627,7 +1627,7 @@ static bool rcu_try_advance_all_cbs(void)
 		 */
 		if (rdp->completed != rnp->completed &&
 		    rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_NEXT_TAIL])
-			rcu_process_gp_end(rsp, rdp);
+			note_gp_changes(rsp, rdp);
 
 		if (cpu_has_callbacks_ready_to_invoke(rdp))
 			cbs_ready = true;
-- 
1.8.1.5

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