The following commit has been merged into the core/rcu branch of tip:
Commit-ID: f042a436c8dc9f9cfe8ed1ee5de372697269657d
Gitweb: https://git.kernel.org/tip/f042a436c8dc9f9cfe8ed1ee5de372697269657d
Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate: Fri, 03 Jan 2020 16:27:00 -08:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Thu, 20 Feb 2020 16:03:31 -08:00
rcutorture: Add READ_ONCE() to rcu_torture_count and rcu_torture_batch
The rcutorture rcu_torture_count and rcu_torture_batch per-CPU variables
are read locklessly, so this commit adds the READ_ONCE() to a load in
order to avoid various types of compiler vandalism^Woptimization.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely and due to this being rcutorture.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/rcutorture.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 124160a..0b9ce9a 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1413,8 +1413,8 @@ rcu_torture_stats_print(void)
for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
- pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
- batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
+ pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
+ batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
}
}
for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
|