linux-kernel - [PATCH v2 1/3] maple_tree: Fix get wrong data_end in mtree_lookup

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Message-Id: <20230314124203.91572-2-zhangpeng.00@bytedance.com>
Date:   Tue, 14 Mar 2023 20:42:01 +0800
From:   Peng Zhang <zhangpeng.00@...edance.com>
To:     Liam.Howlett@...cle.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        maple-tree@...ts.infradead.org,
        Peng Zhang <zhangpeng.00@...edance.com>
Subject: [PATCH v2 1/3] maple_tree: Fix get wrong data_end in mtree_lookup_walk()

if (likely(offset > end))
	max = pivots[offset];

The above code should be changed to if (likely(offset < end)), which is
correct. This affects the correctness of ma_data_end(). Now it seems
that the final result will not be wrong, but it is best to change it.
This patch does not change the code as above, because it simplifies the
code by the way.

Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 646297cae5d1..b3164266cfde 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3875,18 +3875,13 @@ static inline void *mtree_lookup_walk(struct ma_state *mas)
 		end = ma_data_end(node, type, pivots, max);
 		if (unlikely(ma_dead_node(node)))
 			goto dead_node;
-
-		if (pivots[offset] >= mas->index)
-			goto next;
-
 		do {
-			offset++;
-		} while ((offset < end) && (pivots[offset] < mas->index));
-
-		if (likely(offset > end))
-			max = pivots[offset];
+			if (pivots[offset] >= mas->index) {
+				max = pivots[offset];
+				break;
+			}
+		} while (++offset < end);
 
-next:
 		slots = ma_slots(node, type);
 		next = mt_slot(mas->tree, slots, offset);
 		if (unlikely(ma_dead_node(node)))
-- 
2.20.1