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From:   Will Deacon <will@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     Will Deacon <will@kernel.org>, Eric Dumazet <edumazet@google.com>,
        Jann Horn <jannh@google.com>,
        Kees Cook <keescook@chromium.org>,
        Maddie Stone <maddiestone@google.com>,
        Marco Elver <elver@google.com>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>, kernel-team@android.com,
        kernel-hardening@lists.openwall.com
Subject: [RFC PATCH 12/21] list: Poison ->next pointer for non-RCU deletion of 'hlist_nulls_node'
Date:   Tue, 24 Mar 2020 15:36:34 +0000
Message-Id: <20200324153643.15527-13-will@kernel.org>
In-Reply-To: <20200324153643.15527-1-will@kernel.org>
References: <20200324153643.15527-1-will@kernel.org>
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hlist_nulls_del() is used for non-RCU deletion of an 'hlist_nulls_node'
and so we can safely poison the ->next pointer without having to worry
about concurrent readers, just like we do for other non-RCU list
deletion primitives

Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
 include/linux/list_nulls.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index fd154ceb5b0d..48f33ae16381 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -99,6 +99,7 @@ static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
 static inline void hlist_nulls_del(struct hlist_nulls_node *n)
 {
 	__hlist_nulls_del(n);
+	n->next = LIST_POISON1;
 	n->pprev = LIST_POISON2;
 }
 
-- 
2.20.1