linux-kernel - [PATCH v2 06/33] maple_tree: Add smp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230127194110.533103-7-surenb@google.com>
Date:   Fri, 27 Jan 2023 11:40:43 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net,
        dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
        peterz@...radead.org, ldufour@...ux.ibm.com, paulmck@...nel.org,
        mingo@...hat.com, will@...nel.org, luto@...nel.org,
        songliubraving@...com, peterx@...hat.com, david@...hat.com,
        dhowells@...hat.com, hughd@...gle.com, bigeasy@...utronix.de,
        kent.overstreet@...ux.dev, punit.agrawal@...edance.com,
        lstoakes@...il.com, peterjung1337@...il.com, rientjes@...gle.com,
        axelrasmussen@...gle.com, joelaf@...gle.com, minchan@...gle.com,
        rppt@...nel.org, jannh@...gle.com, shakeelb@...gle.com,
        tatashin@...gle.com, edumazet@...gle.com, gthelen@...gle.com,
        gurua@...gle.com, arjunroy@...gle.com, soheil@...gle.com,
        leewalsh@...gle.com, posk@...gle.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        surenb@...gle.com, "Liam R. Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v2 06/33] maple_tree: Add smp_rmb() to dead node detection

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

Add an smp_rmb() before reading the parent pointer to ensure that
anything read from the node prior to the parent pointer hasn't been
reordered ahead of this check.

The is necessary for RCU mode.

Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 lib/maple_tree.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 49e399e8afaa..859303d2da90 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -532,9 +532,11 @@ static inline struct maple_node *mte_parent(const struct maple_enode *enode)
  */
 static inline bool ma_dead_node(const struct maple_node *node)
 {
-	struct maple_node *parent = (void *)((unsigned long)
-					     node->parent & ~MAPLE_NODE_MASK);
+	struct maple_node *parent;
 
+	/* Do not reorder reads from the node prior to the parent check */
+	smp_rmb();
+	parent = (void *)((unsigned long) node->parent & ~MAPLE_NODE_MASK);
 	return (parent == node);
 }
 
@@ -549,6 +551,8 @@ static inline bool mte_dead_node(const struct maple_enode *enode)
 	struct maple_node *parent, *node;
 
 	node = mte_to_node(enode);
+	/* Do not reorder reads from the node prior to the parent check */
+	smp_rmb();
 	parent = mte_parent(enode);
 	return (parent == node);
 }
-- 
2.39.1