From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
[ Upstream commit a24c1aab652ebacf9ea62470a166514174c96fe1 ]
The rcu_data structure's ->rcu_cpu_has_work field can be modified by
any CPU attempting to wake up the rcuc kthread. Therefore, this commit
marks accesses to this field from the rcu_cpu_kthread() function.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/rcu/tree.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a565dc5c54440..fbba4161060cd 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2455,12 +2455,12 @@ static void rcu_cpu_kthread(unsigned int cpu)
*statusp = RCU_KTHREAD_RUNNING;
local_irq_disable();
work = *workp;
- *workp = 0;
+ WRITE_ONCE(*workp, 0);
local_irq_enable();
if (work)
rcu_core();
local_bh_enable();
- if (*workp == 0) {
+ if (!READ_ONCE(*workp)) {
trace_rcu_utilization(TPS("End CPU kthread@rcu_wait"));
*statusp = RCU_KTHREAD_WAITING;
return;
--
2.39.2
