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authorPaul E. McKenney <paulmck@kernel.org>2019-12-22 19:55:50 -0800
committerPaul E. McKenney <paulmck@kernel.org>2020-02-20 15:58:21 -0800
commit24bb9eccf7ff335c16c2970ac7cd5c32a92821a6 (patch)
tree149776c467fb08dc619d26f77565ac3b90b31a8d /kernel/rcu/tree_exp.h
parent82dd8419e225958f01708cda8a3fc6c3c5356228 (diff)
rcu: Fix exp_funnel_lock()/rcu_exp_wait_wake() datarace
The rcu_node structure's ->exp_seq_rq field is accessed locklessly, so updates must use WRITE_ONCE(). This commit therefore adds the needed WRITE_ONCE() invocation where it was missed. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree_exp.h')
-rw-r--r--kernel/rcu/tree_exp.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index dcbd75791f39..d7e04849c7ab 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -589,7 +589,7 @@ static void rcu_exp_wait_wake(unsigned long s)
spin_lock(&rnp->exp_lock);
/* Recheck, avoid hang in case someone just arrived. */
if (ULONG_CMP_LT(rnp->exp_seq_rq, s))
- rnp->exp_seq_rq = s;
+ WRITE_ONCE(rnp->exp_seq_rq, s);
spin_unlock(&rnp->exp_lock);
}
smp_mb(); /* All above changes before wakeup. */