linux-kernel - [PATCH 1/2] maple_tree: Add mas_active() to detect in-tree walks

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Date:   Thu, 21 Sep 2023 14:12:35 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, pedro.falcato@...il.com,
        stable <stable@...nel.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH 1/2] maple_tree: Add mas_active() to detect in-tree walks

Instead of constantly checking each possibility of the maple state,
create a fast path that will skip over checking unlikely states.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 include/linux/maple_tree.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e41c70ac7744..f66f5f78f8cf 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -511,6 +511,15 @@ static inline bool mas_is_paused(const struct ma_state *mas)
 	return mas->node == MAS_PAUSE;
 }
 
+/* Check if the mas is pointing to a node or not */
+static inline bool mas_is_active(struct ma_state *mas)
+{
+	if ((unsigned long)mas->node >= MAPLE_RESERVED_RANGE)
+		return true;
+
+	return false;
+}
+
 /**
  * mas_reset() - Reset a Maple Tree operation state.
  * @mas: Maple Tree operation state.
-- 
2.39.2