Commit 102c14d2 authored Dec 21, 2019 by Paul E. McKenney

rcutorture: Fix stray access to rcu_fwd_cb_nodelay



The rcu_fwd_cb_nodelay variable suppresses excessively long read-side
delays while carrying out an rcutorture forward-progress test.  As such,
it is accessed both by readers and updaters, and most of the accesses
therefore use *_ONCE().  Except for one in rcu_read_delay(), which this
commit fixes.

This data race was reported by KCSAN.  Not appropriate for backporting
due to this being rcutorture.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

parent 20248910

kernel/rcu/rcutorture.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -339,7 +339,7 @@ rcu_read_delay(struct torture_random_state rrsp, struct rt_read_seg rtrsp)
		* period, and we want a long delay occasionally to trigger
		* force_quiescent_state. */

		if (!rcu_fwd_cb_nodelay &&
		if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
		!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
		started = cur_ops->get_gp_seq();
		ts = rcu_trace_clock_local();

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