linux-kernel - [PATCH 6.1 11/14] maple_tree: remove extra smp_wmb() from mas_dead

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Date:   Tue, 11 Apr 2023 11:10:52 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org
Cc:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Liam Howlett <Liam.Howlett@...cle.com>
Subject: [PATCH 6.1 11/14] maple_tree: remove extra smp_wmb() from mas_dead_leaves()

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

commit 8372f4d83f96f35915106093cde4565836587123 upstream.

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 0f0a2d4850e8..281be0997e55 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5501,7 +5501,6 @@ 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