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rcutorture: Replace barriers with smp_store_release() and smp_load_acquire()
The rcutorture.c file uses several explicit memory barriers that can easily be converted to smp_store_release() and smp_load_acquire(), which improves maintainability and also improves performance a bit. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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1 changed files with 13 additions and 11 deletions
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@ -672,8 +672,8 @@ static void rcu_torture_boost_cb(struct rcu_head *head)
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struct rcu_boost_inflight *rbip =
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container_of(head, struct rcu_boost_inflight, rcu);
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smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
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rbip->inflight = 0;
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/* Ensure RCU-core accesses precede clearing ->inflight */
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smp_store_release(&rbip->inflight, 0);
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}
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static int rcu_torture_boost(void *arg)
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@ -710,9 +710,9 @@ static int rcu_torture_boost(void *arg)
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call_rcu_time = jiffies;
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while (ULONG_CMP_LT(jiffies, endtime)) {
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/* If we don't have a callback in flight, post one. */
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if (!rbi.inflight) {
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smp_mb(); /* RCU core before ->inflight = 1. */
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rbi.inflight = 1;
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if (!smp_load_acquire(&rbi.inflight)) {
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/* RCU core before ->inflight = 1. */
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smp_store_release(&rbi.inflight, 1);
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call_rcu(&rbi.rcu, rcu_torture_boost_cb);
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if (jiffies - call_rcu_time >
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test_boost_duration * HZ - HZ / 2) {
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@ -751,11 +751,10 @@ checkwait: stutter_wait("rcu_torture_boost");
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} while (!torture_must_stop());
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/* Clean up and exit. */
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while (!kthread_should_stop() || rbi.inflight) {
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while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
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torture_shutdown_absorb("rcu_torture_boost");
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schedule_timeout_uninterruptible(1);
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}
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smp_mb(); /* order accesses to ->inflight before stack-frame death. */
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destroy_rcu_head_on_stack(&rbi.rcu);
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torture_kthread_stopping("rcu_torture_boost");
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return 0;
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@ -1413,12 +1412,15 @@ static int rcu_torture_barrier_cbs(void *arg)
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do {
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wait_event(barrier_cbs_wq[myid],
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(newphase =
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READ_ONCE(barrier_phase)) != lastphase ||
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smp_load_acquire(&barrier_phase)) != lastphase ||
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torture_must_stop());
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lastphase = newphase;
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smp_mb(); /* ensure barrier_phase load before ->call(). */
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if (torture_must_stop())
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break;
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/*
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* The above smp_load_acquire() ensures barrier_phase load
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* is ordered before the folloiwng ->call().
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*/
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cur_ops->call(&rcu, rcu_torture_barrier_cbf);
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if (atomic_dec_and_test(&barrier_cbs_count))
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wake_up(&barrier_wq);
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@ -1439,8 +1441,8 @@ static int rcu_torture_barrier(void *arg)
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do {
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atomic_set(&barrier_cbs_invoked, 0);
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atomic_set(&barrier_cbs_count, n_barrier_cbs);
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smp_mb(); /* Ensure barrier_phase after prior assignments. */
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barrier_phase = !barrier_phase;
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/* Ensure barrier_phase ordered after prior assignments. */
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smp_store_release(&barrier_phase, !barrier_phase);
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for (i = 0; i < n_barrier_cbs; i++)
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wake_up(&barrier_cbs_wq[i]);
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wait_event(barrier_wq,
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