linux-kernel - [PATCH 4/8] maple_tree: remove extra smp_wmb() from mas_dead

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Date:   Mon, 27 Mar 2023 14:55:28 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
        Suren Baghdasaryan <surenb@...gle.com>
Cc:     "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        stable@...r.kernel.org, Liam Howlett <Liam.Howlett@...cle.com>
Subject: [PATCH 4/8] maple_tree: remove extra smp_wmb() from mas_dead_leaves()

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

The call to mte_set_dead_node() before the smp_wmb() already calls
smp_wmb() so this is not needed.  This is an optimization for the RCU mode
of the maple tree.

Link: https://lkml.kernel.org/r/20230227173632.3292573-5-surenb@google.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: stable@...r.kernel.org
Signed-off-by: Liam Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 44d6ce30b28e..3d5ab02f981a 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5517,7 +5517,6 @@ unsigned char mas_dead_leaves(struct ma_state *mas, void __rcu **slots,
 			break;
 
 		mte_set_node_dead(entry);
-		smp_wmb(); /* Needed for RCU */
 		node->type = type;
 		rcu_assign_pointer(slots[offset], node);
 	}
-- 
2.39.2