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Subject[PATCH rcu 2/3] rcu: Mark ->expmask access in synchronize_rcu_expedited_wait()
Date
This commit adds a READ_ONCE() to an access to the rcu_node structure's
->expmask field to prevent compiler mischief. Detected by KCSAN.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree_exp.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 1568c8ef185b2..60197ea24ceb9 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -502,7 +502,8 @@ static void synchronize_rcu_expedited_wait(void)
if (synchronize_rcu_expedited_wait_once(1))
return;
rcu_for_each_leaf_node(rnp) {
- for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
+ mask = READ_ONCE(rnp->expmask);
+ for_each_leaf_node_cpu_mask(rnp, cpu, mask) {
rdp = per_cpu_ptr(&rcu_data, cpu);
if (rdp->rcu_forced_tick_exp)
continue;
--
2.31.1.189.g2e36527f23
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