From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 4/4] srcu: Add READ_ONCE() to srcu_struct ->srcu_gp_seq load
Date: Fri, 14 Feb 2020 16:29:32 -0800 [thread overview]
Message-ID: <20200215002932.15976-4-paulmck@kernel.org> (raw)
In-Reply-To: <20200215002907.GA15895@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@kernel.org>
The load of the srcu_struct structure's ->srcu_gp_seq field in
srcu_funnel_gp_start() is lockless, so this commit adds the requisite
READ_ONCE().
This data race was reported by KCSAN.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 119a373..90ab475 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -678,7 +678,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp,
/* If grace period not already done and none in progress, start it. */
if (!rcu_seq_done(&ssp->srcu_gp_seq, s) &&
- rcu_seq_state(ssp->srcu_gp_seq) == SRCU_STATE_IDLE) {
+ rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) == SRCU_STATE_IDLE) {
WARN_ON_ONCE(ULONG_CMP_GE(ssp->srcu_gp_seq, ssp->srcu_gp_seq_needed));
srcu_gp_start(ssp);
if (likely(srcu_init_done))
--
2.9.5
next prev parent reply other threads:[~2020-02-15 0:29 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-15 0:29 [PATCH tip/core/rcu 0/4] SRCU updates for v5.7 Paul E. McKenney
2020-02-15 0:29 ` [PATCH tip/core/rcu 1/4] srcu: Fix __call_srcu()/process_srcu() datarace paulmck
2020-02-17 12:42 ` Peter Zijlstra
2020-02-17 17:01 ` Joel Fernandes
2020-02-17 17:11 ` Peter Zijlstra
2020-02-17 17:46 ` Joel Fernandes
2020-02-17 18:18 ` Paul E. McKenney
2020-02-15 0:29 ` [PATCH tip/core/rcu 2/4] srcu: Fix __call_srcu()/srcu_get_delay() datarace paulmck
2020-02-15 0:29 ` [PATCH tip/core/rcu 3/4] srcu: Fix process_srcu()/srcu_batches_completed() datarace paulmck
2020-02-15 0:29 ` paulmck [this message]
2020-02-17 12:45 ` [PATCH tip/core/rcu 4/4] srcu: Add READ_ONCE() to srcu_struct ->srcu_gp_seq load Peter Zijlstra
2020-02-17 18:32 ` Paul E. McKenney
2020-02-17 23:06 ` Paul E. McKenney
2020-02-18 11:46 ` Peter Zijlstra
2020-02-18 21:48 ` Paul E. McKenney
2020-02-18 11:43 ` Peter Zijlstra
2020-02-18 16:34 ` Paul E. McKenney
2020-02-18 20:26 ` Peter Zijlstra
2020-02-18 21:38 ` Paul E. McKenney
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