linux-kernel - [PATCH] srcu: Remove srcu_cblist

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Message-Id: <20201119053411.11698-1-qiang.zhang@windriver.com>
Date:   Thu, 19 Nov 2020 13:34:11 +0800
From:   qiang.zhang@...driver.com
To:     paulmck@...nel.org
Cc:     jiangshanlai@...il.com, rostedt@...dmis.org, josh@...htriplett.org,
        rcu@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] srcu: Remove srcu_cblist_invoking member from sdp

From: Zqiang <qiang.zhang@...driver.com>

Workqueue can ensure the multiple same sdp->work sequential
execution in rcu_gp_wq, not need srcu_cblist_invoking to
prevent concurrent execution, so remove it.

Signed-off-by: Zqiang <qiang.zhang@...driver.com>
---
 include/linux/srcutree.h | 1 -
 kernel/rcu/srcutree.c    | 8 ++------
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 9cfcc8a756ae..62d8312b5451 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -31,7 +31,6 @@ struct srcu_data {
 	struct rcu_segcblist srcu_cblist;	/* List of callbacks.*/
 	unsigned long srcu_gp_seq_needed;	/* Furthest future GP needed. */
 	unsigned long srcu_gp_seq_needed_exp;	/* Furthest future exp GP. */
-	bool srcu_cblist_invoking;		/* Invoking these CBs? */
 	struct timer_list delay_work;		/* Delay for CB invoking */
 	struct work_struct work;		/* Context for CB invoking. */
 	struct rcu_head srcu_barrier_head;	/* For srcu_barrier() use. */
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 3c5e2806e0b9..c4d5cd2567a6 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -134,7 +134,6 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
 		sdp = per_cpu_ptr(ssp->sda, cpu);
 		spin_lock_init(&ACCESS_PRIVATE(sdp, lock));
 		rcu_segcblist_init(&sdp->srcu_cblist);
-		sdp->srcu_cblist_invoking = false;
 		sdp->srcu_gp_seq_needed = ssp->srcu_gp_seq;
 		sdp->srcu_gp_seq_needed_exp = ssp->srcu_gp_seq;
 		sdp->mynode = &snp_first[cpu / levelspread[level]];
@@ -1254,14 +1253,11 @@ static void srcu_invoke_callbacks(struct work_struct *work)
 	spin_lock_irq_rcu_node(sdp);
 	rcu_segcblist_advance(&sdp->srcu_cblist,
 			      rcu_seq_current(&ssp->srcu_gp_seq));
-	if (sdp->srcu_cblist_invoking ||
-	    !rcu_segcblist_ready_cbs(&sdp->srcu_cblist)) {
+	if (!rcu_segcblist_ready_cbs(&sdp->srcu_cblist)) {
 		spin_unlock_irq_rcu_node(sdp);
 		return;  /* Someone else on the job or nothing to do. */
 	}
 
-	/* We are on the job!  Extract and invoke ready callbacks. */
-	sdp->srcu_cblist_invoking = true;
 	rcu_segcblist_extract_done_cbs(&sdp->srcu_cblist, &ready_cbs);
 	len = ready_cbs.len;
 	spin_unlock_irq_rcu_node(sdp);
@@ -1282,7 +1278,7 @@ static void srcu_invoke_callbacks(struct work_struct *work)
 	rcu_segcblist_add_len(&sdp->srcu_cblist, -len);
 	(void)rcu_segcblist_accelerate(&sdp->srcu_cblist,
 				       rcu_seq_snap(&ssp->srcu_gp_seq));
-	sdp->srcu_cblist_invoking = false;
+
 	more = rcu_segcblist_ready_cbs(&sdp->srcu_cblist);
 	spin_unlock_irq_rcu_node(sdp);
 	if (more)
-- 
2.17.1