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rcutorture: Fix stray access to rcu_fwd_cb_nodelay

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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>
This commit is contained in:
Paul E. McKenney 2019-12-21 11:23:50 -08:00
parent 202489101f
commit 102c14d2f8
1 changed files with 1 additions and 1 deletions
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2
kernel/rcu/rcutorture.c
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@ -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 * period, and we want a long delay occasionally to trigger
* force_quiescent_state. */ * force_quiescent_state. */
if (!rcu_fwd_cb_nodelay && if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) { !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
started = cur_ops->get_gp_seq(); started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local(); ts = rcu_trace_clock_local();