torture: Remove support for SRCU-lite

Because SRCU-lite is being replaced by SRCU-fast, this commit removes
support for SRCU-lite from refscale.c.

Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period.  There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.

[ paulmck: Apply Christoph Hellwig feedback. ]

Signed-off-by: "Paul E. McKenney" <[email protected]>
Signed-off-by: Neeraj Upadhyay (AMD) <[email protected]>

Author: paulmckrcu

kernel/rcu/refscale.c

@@ -246,36 +246,6 @@ static const struct ref_scale_ops srcu_fast_ops = {
 	.name		= "srcu-fast"
 };
 
-static void srcu_lite_ref_scale_read_section(const int nloops)
-{
-	int i;
-	int idx;
-
-	for (i = nloops; i >= 0; i--) {
-		idx = srcu_read_lock_lite(srcu_ctlp);
-		srcu_read_unlock_lite(srcu_ctlp, idx);
-	}
-}
-
-static void srcu_lite_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
-{
-	int i;
-	int idx;
-
-	for (i = nloops; i >= 0; i--) {
-		idx = srcu_read_lock_lite(srcu_ctlp);
-		un_delay(udl, ndl);
-		srcu_read_unlock_lite(srcu_ctlp, idx);
-	}
-}
-
-static const struct ref_scale_ops srcu_lite_ops = {
-	.init		= rcu_sync_scale_init,
-	.readsection	= srcu_lite_ref_scale_read_section,
-	.delaysection	= srcu_lite_ref_scale_delay_section,
-	.name		= "srcu-lite"
-};
-
 #ifdef CONFIG_TASKS_RCU
 
 // Definitions for RCU Tasks ref scale testing: Empty read markers.
@@ -1193,7 +1163,7 @@ ref_scale_init(void)
 	long i;
 	int firsterr = 0;
 	static const struct ref_scale_ops *scale_ops[] = {
-		&rcu_ops, &srcu_ops, &srcu_fast_ops, &srcu_lite_ops, RCU_TRACE_OPS RCU_TASKS_OPS
+		&rcu_ops, &srcu_ops, &srcu_fast_ops, RCU_TRACE_OPS RCU_TASKS_OPS
 		&refcnt_ops, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops,
 		&acqrel_ops, &sched_clock_ops, &clock_ops, &jiffies_ops,
 		&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,