patches/treercu-use-simple-waitqueue.patch

From db7ae440c333156392bc56badc610469a4d522ae Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 8 Apr 2013 16:09:57 +0200
Subject: [PATCH] kernel/treercu: use a simple waitqueue

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/rcutree.c |   13 +++++++------
 kernel/rcutree.h |    2 +-
 2 files changed, 8 insertions(+), 7 deletions(-)

--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1319,7 +1319,7 @@ static int __noreturn rcu_gp_kthread(voi
 
 		/* Handle grace-period start. */
 		for (;;) {
-			wait_event_interruptible(rsp->gp_wq,
+			swait_event_interruptible(rsp->gp_wq,
 						 rsp->gp_flags &
 						 RCU_GP_FLAG_INIT);
 			if ((rsp->gp_flags & RCU_GP_FLAG_INIT) &&
@@ -1338,7 +1338,7 @@ static int __noreturn rcu_gp_kthread(voi
 		}
 		for (;;) {
 			rsp->jiffies_force_qs = jiffies + j;
-			ret = wait_event_interruptible_timeout(rsp->gp_wq,
+			ret = swait_event_interruptible_timeout(rsp->gp_wq,
 					(rsp->gp_flags & RCU_GP_FLAG_FQS) ||
 					(!ACCESS_ONCE(rnp->qsmask) &&
 					 !rcu_preempt_blocked_readers_cgp(rnp)),
@@ -1423,7 +1423,7 @@ rcu_start_gp(struct rcu_state *rsp, unsi
 	local_irq_restore(flags);
 
 	/* Wake up rcu_gp_kthread() to start the grace period. */
-	wake_up(&rsp->gp_wq);
+	swait_wake(&rsp->gp_wq);
 }
 
 /*
@@ -1438,7 +1438,7 @@ static void rcu_report_qs_rsp(struct rcu
 {
 	WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
 	raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
-	wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
+	swait_wake(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
 }
 
 /*
@@ -2003,7 +2003,8 @@ static void force_quiescent_state(struct
 	}
 	rsp->gp_flags |= RCU_GP_FLAG_FQS;
 	raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
-	wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
+	/* Memory barrier implied by wake_up() path. */
+	swait_wake(&rsp->gp_wq);
 }
 
 /*
@@ -2999,7 +3000,7 @@ static void __init rcu_init_one(struct r
 	}
 
 	rsp->rda = rda;
-	init_waitqueue_head(&rsp->gp_wq);
+	init_swait_head(&rsp->gp_wq);
 	rnp = rsp->level[rcu_num_lvls - 1];
 	for_each_possible_cpu(i) {
 		while (i > rnp->grphi)
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -397,7 +397,7 @@ struct rcu_state {
 	unsigned long gpnum;			/* Current gp number. */
 	unsigned long completed;		/* # of last completed gp. */
 	struct task_struct *gp_kthread;		/* Task for grace periods. */
-	wait_queue_head_t gp_wq;		/* Where GP task waits. */
+	struct swait_head gp_wq;		/* Where GP task waits. */
 	int gp_flags;				/* Commands for GP task. */
 
 	/* End of fields guarded by root rcu_node's lock. */