rt-patches/0142-rcu-use-simple-waitqueues.patch

From 70fffb9a5b9e7c38b15b714a9b5df3b944f1f6e9 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 31 Jul 2013 19:00:35 +0200
Subject: [PATCH 142/366] rcu: use simple waitqueues

Convert RCU's wait-queues into simple waitqueues.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Merged Steven's

 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) {
-       swait_wake(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
+       wake_up_all(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
 }

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/rcu/tree.c        | 16 ++++++++--------
 kernel/rcu/tree.h        |  9 +++++----
 kernel/rcu/tree_plugin.h | 18 +++++++++---------
 3 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 136eb953..a0b2db4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1633,7 +1633,7 @@ static void rcu_gp_kthread_wake(struct rcu_state *rsp)
 	    !READ_ONCE(rsp->gp_flags) ||
 	    !rsp->gp_kthread)
 		return;
-	wake_up(&rsp->gp_wq);
+	swait_wake(&rsp->gp_wq);
 }
 
 /*
@@ -2098,7 +2098,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
 					       READ_ONCE(rsp->gpnum),
 					       TPS("reqwait"));
 			rsp->gp_state = RCU_GP_WAIT_GPS;
-			wait_event_interruptible(rsp->gp_wq,
+			swait_event_interruptible(rsp->gp_wq,
 						 READ_ONCE(rsp->gp_flags) &
 						 RCU_GP_FLAG_INIT);
 			rsp->gp_state = RCU_GP_DONE_GPS;
@@ -2128,7 +2128,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
 					       READ_ONCE(rsp->gpnum),
 					       TPS("fqswait"));
 			rsp->gp_state = RCU_GP_WAIT_FQS;
-			ret = wait_event_interruptible_timeout(rsp->gp_wq,
+			ret = swait_event_interruptible_timeout(rsp->gp_wq,
 					rcu_gp_fqs_check_wake(rsp, &gf), j);
 			rsp->gp_state = RCU_GP_DOING_FQS;
 			/* Locking provides needed memory barriers. */
@@ -3550,7 +3550,7 @@ static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
 			raw_spin_unlock_irqrestore(&rnp->lock, flags);
 			if (wake) {
 				smp_mb(); /* EGP done before wake_up(). */
-				wake_up(&rsp->expedited_wq);
+				swait_wake(&rsp->expedited_wq);
 			}
 			break;
 		}
@@ -3807,7 +3807,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
 	jiffies_start = jiffies;
 
 	for (;;) {
-		ret = wait_event_interruptible_timeout(
+		ret = swait_event_interruptible_timeout(
 				rsp->expedited_wq,
 				sync_rcu_preempt_exp_done(rnp_root),
 				jiffies_stall);
@@ -3815,7 +3815,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
 			return;
 		if (ret < 0) {
 			/* Hit a signal, disable CPU stall warnings. */
-			wait_event(rsp->expedited_wq,
+			swait_event(rsp->expedited_wq,
 				   sync_rcu_preempt_exp_done(rnp_root));
 			return;
 		}
@@ -4483,8 +4483,8 @@ static void __init rcu_init_one(struct rcu_state *rsp,
 		}
 	}
 
-	init_waitqueue_head(&rsp->gp_wq);
-	init_waitqueue_head(&rsp->expedited_wq);
+	init_swait_head(&rsp->gp_wq);
+	init_swait_head(&rsp->expedited_wq);
 	rnp = rsp->level[rcu_num_lvls - 1];
 	for_each_possible_cpu(i) {
 		while (i > rnp->grphi)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 9fb4e23..e7e0939 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -28,6 +28,7 @@
 #include <linux/cpumask.h>
 #include <linux/seqlock.h>
 #include <linux/stop_machine.h>
+#include <linux/wait-simple.h>
 
 /*
  * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
@@ -241,7 +242,7 @@ struct rcu_node {
 				/* Refused to boost: not sure why, though. */
 				/*  This can happen due to race conditions. */
 #ifdef CONFIG_RCU_NOCB_CPU
-	wait_queue_head_t nocb_gp_wq[2];
+	struct swait_head nocb_gp_wq[2];
 				/* Place for rcu_nocb_kthread() to wait GP. */
 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
 	int need_future_gp[2];
@@ -393,7 +394,7 @@ struct rcu_data {
 	atomic_long_t nocb_q_count_lazy; /*  invocation (all stages). */
 	struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
 	struct rcu_head **nocb_follower_tail;
-	wait_queue_head_t nocb_wq;	/* For nocb kthreads to sleep on. */
+	struct swait_head nocb_wq;	/* For nocb kthreads to sleep on. */
 	struct task_struct *nocb_kthread;
 	int nocb_defer_wakeup;		/* Defer wakeup of nocb_kthread. */
 
@@ -472,7 +473,7 @@ 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. */
 	short gp_flags;				/* Commands for GP task. */
 	short gp_state;				/* GP kthread sleep state. */
 
@@ -504,7 +505,7 @@ struct rcu_state {
 	atomic_long_t expedited_workdone3;	/* # done by others #3. */
 	atomic_long_t expedited_normal;		/* # fallbacks to normal. */
 	atomic_t expedited_need_qs;		/* # CPUs left to check in. */
-	wait_queue_head_t expedited_wq;		/* Wait for check-ins. */
+	struct swait_head expedited_wq;		/* Wait for check-ins. */
 	int ncpus_snap;				/* # CPUs seen last time. */
 
 	unsigned long jiffies_force_qs;		/* Time at which to invoke */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 019a1eb5..86af123 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1830,7 +1830,7 @@ early_param("rcu_nocb_poll", parse_rcu_nocb_poll);
  */
 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
 {
-	wake_up_all(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
+	swait_wake_all(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
 }
 
 /*
@@ -1848,8 +1848,8 @@ static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq)
 
 static void rcu_init_one_nocb(struct rcu_node *rnp)
 {
-	init_waitqueue_head(&rnp->nocb_gp_wq[0]);
-	init_waitqueue_head(&rnp->nocb_gp_wq[1]);
+	init_swait_head(&rnp->nocb_gp_wq[0]);
+	init_swait_head(&rnp->nocb_gp_wq[1]);
 }
 
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
@@ -1874,7 +1874,7 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool force)
 	if (READ_ONCE(rdp_leader->nocb_leader_sleep) || force) {
 		/* Prior smp_mb__after_atomic() orders against prior enqueue. */
 		WRITE_ONCE(rdp_leader->nocb_leader_sleep, false);
-		wake_up(&rdp_leader->nocb_wq);
+		swait_wake(&rdp_leader->nocb_wq);
 	}
 }
 
@@ -2087,7 +2087,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
 	 */
 	trace_rcu_future_gp(rnp, rdp, c, TPS("StartWait"));
 	for (;;) {
-		wait_event_interruptible(
+		swait_event_interruptible(
 			rnp->nocb_gp_wq[c & 0x1],
 			(d = ULONG_CMP_GE(READ_ONCE(rnp->completed), c)));
 		if (likely(d))
@@ -2115,7 +2115,7 @@ wait_again:
 	/* Wait for callbacks to appear. */
 	if (!rcu_nocb_poll) {
 		trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu, "Sleep");
-		wait_event_interruptible(my_rdp->nocb_wq,
+		swait_event_interruptible(my_rdp->nocb_wq,
 				!READ_ONCE(my_rdp->nocb_leader_sleep));
 		/* Memory barrier handled by smp_mb() calls below and repoll. */
 	} else if (firsttime) {
@@ -2190,7 +2190,7 @@ wait_again:
 			 * List was empty, wake up the follower.
 			 * Memory barriers supplied by atomic_long_add().
 			 */
-			wake_up(&rdp->nocb_wq);
+			swait_wake(&rdp->nocb_wq);
 		}
 	}
 
@@ -2211,7 +2211,7 @@ static void nocb_follower_wait(struct rcu_data *rdp)
 		if (!rcu_nocb_poll) {
 			trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
 					    "FollowerSleep");
-			wait_event_interruptible(rdp->nocb_wq,
+			swait_event_interruptible(rdp->nocb_wq,
 						 READ_ONCE(rdp->nocb_follower_head));
 		} else if (firsttime) {
 			/* Don't drown trace log with "Poll"! */
@@ -2371,7 +2371,7 @@ void __init rcu_init_nohz(void)
 static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
 {
 	rdp->nocb_tail = &rdp->nocb_head;
-	init_waitqueue_head(&rdp->nocb_wq);
+	init_swait_head(&rdp->nocb_wq);
 	rdp->nocb_follower_tail = &rdp->nocb_follower_head;
 }
 
-- 
1.9.1