From c9527bebb017b891d1a2bbb96217bd5225488a0e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 18 Feb 2020 13:41:02 -0800 Subject: rcutorture: Mark data-race potential for rcu_barrier() test statistics The n_barrier_successes, n_barrier_attempts, and n_rcu_torture_barrier_error variables are updated (without access markings) by the main rcu_barrier() test kthread, and accessed (also without access markings) by the rcu_torture_stats() kthread. This of course can result in KCSAN complaints. Because the accesses are in diagnostic prints, this commit uses data_race() to excuse the diagnostic prints from the data race. If this were to ever cause bogus statistics prints (for example, due to store tearing), any misleading information would be disambiguated by the presence or absence of an rcutorture splat. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to the mild consequences of the failure, namely a confusing rcutorture console message. Signed-off-by: Paul E. McKenney Reviewed-by: Joel Fernandes (Google) --- kernel/rcu/rcutorture.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 7e2ea0c57433..d0345d14e22a 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1456,9 +1456,9 @@ rcu_torture_stats_print(void) atomic_long_read(&n_rcu_torture_timers)); torture_onoff_stats(); pr_cont("barrier: %ld/%ld:%ld\n", - n_barrier_successes, - n_barrier_attempts, - n_rcu_torture_barrier_error); + data_race(n_barrier_successes), + data_race(n_barrier_attempts), + data_race(n_rcu_torture_barrier_error)); pr_alert("%s%s ", torture_type, TORTURE_FLAG); if (atomic_read(&n_rcu_torture_mberror) || -- cgit v1.2.3-59-g8ed1b