From: Paul E. McKenney <paulmck@xxxxxxxxxx>
[ Upstream commit c09929031018913b5783872a8b8cdddef4a543c7 ]
KCSAN reports data races between the rcu_segcblist_clear_flags() and
rcu_segcblist_set_flags() functions, though misreporting the latter
as a call to rcu_segcblist_is_enabled() from call_rcu(). This commit
converts the updates of this field to WRITE_ONCE(), relying on the
resulting unmarked reads to continue to detect buggy concurrent writes
to this field.
Reported-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/rcu/rcu_segcblist.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index e373fbe44da5..431cee212467 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -56,13 +56,13 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
int flags)
{
- rsclp->flags |= flags;
+ WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
}
static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
int flags)
{
- rsclp->flags &= ~flags;
+ WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
}
static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
--
2.34.1
