Commit f042a436 authored Jan 03, 2020 by Paul E. McKenney

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@kernel.org>

parent 102c14d2

kernel/rcu/rcutorture.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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--) {

Admin message