Commit c0992903 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Mark writes to the rcu_segcblist structure's ->flags field 



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: default avatarZhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
parent d818cc76

kernel/rcu/rcu_segcblist.h

+2 −2
Original line number Diff line number Diff line
@@ -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,