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Date: Tue, 24 Mar 2020 15:36:28 +0000
From: Will Deacon <will@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Will Deacon <will@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Jann Horn <jannh@...gle.com>,
Kees Cook <keescook@...omium.org>,
Maddie Stone <maddiestone@...gle.com>,
Marco Elver <elver@...gle.com>,
"Paul E . McKenney" <paulmck@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
kernel-team@...roid.com,
kernel-hardening@...ts.openwall.com
Subject: [RFC PATCH 06/21] list: Remove superfluous WRITE_ONCE() from hlist_nulls implementation
Commit 860c8802ace1 ("rcu: Use WRITE_ONCE() for assignments to ->pprev
for hlist_nulls") added WRITE_ONCE() invocations to hlist_nulls_add_head()
and hlist_nulls_del().
Since these functions should not ordinarily run concurrently with other
list accessors, restore the plain C assignments so that KCSAN can yell
if a data race occurs.
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Will Deacon <will@...nel.org>
---
include/linux/list_nulls.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index fa51a801bf32..fd154ceb5b0d 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -80,10 +80,10 @@ static inline void hlist_nulls_add_head(struct hlist_nulls_node *n,
struct hlist_nulls_node *first = h->first;
n->next = first;
- WRITE_ONCE(n->pprev, &h->first);
+ n->pprev = &h->first;
h->first = n;
if (!is_a_nulls(first))
- WRITE_ONCE(first->pprev, &n->next);
+ first->pprev = &n->next;
}
static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
@@ -99,7 +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);
- WRITE_ONCE(n->pprev, LIST_POISON2);
+ n->pprev = LIST_POISON2;
}
/**
--
2.20.1
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