Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 18 Jan 2018 18:33:43 +0800
From:   "Liu, Changcheng" <changcheng.liu@intel.com>
To:     Lai Jiangshan <jiangshanlai@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc:     linux-kernel@vger.kernel.org, changcheng.liu@intel.com
Subject: [PATCH] rcu: refine structure rcu_node field for rcu boost
Message-ID: <20180118103342.GA114176@sofia>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Do not allocate space for rcu boost field when
RCU BOOST is not configured.

Signed-off-by: Liu Changcheng <changcheng.liu@intel.com>

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 46a5d19..88f087e 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -129,6 +129,7 @@ struct rcu_node {
 				/*  if there is no such task.  If there */
 				/*  is no current expedited grace period, */
 				/*  then there can cannot be any such task. */
+#ifdef CONFIG_RCU_BOOST
 	struct list_head *boost_tasks;
 				/* Pointer to first task that needs to be */
 				/*  priority boosted, or NULL if no priority */
@@ -153,6 +154,8 @@ struct rcu_node {
 				/* Number of tasks boosted for expedited GP. */
 	unsigned long n_normal_boosts;
 				/* Number of tasks boosted for normal GP. */
+#endif/* #ifdef CONFIG_RCU_BOOST*/
+
 #ifdef CONFIG_RCU_NOCB_CPU
 	struct swait_queue_head nocb_gp_wq[2];
 				/* Place for rcu_nocb_kthread() to wait GP. */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index db85ca3..fee0b1e 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -506,8 +506,10 @@ void rcu_read_unlock_special(struct task_struct *t)
 		if (IS_ENABLED(CONFIG_RCU_BOOST)) {
 			/* Snapshot ->boost_mtx ownership w/rnp->lock held. */
 			drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;
+#ifdef CONFIG_RCU_BOOST
 			if (&t->rcu_node_entry == rnp->boost_tasks)
 				rnp->boost_tasks = np;
+#endif
 		}
 
 		/*
-- 
2.7.4