rcutorture: Abstract synchronous and polled API testing

This commit abstracts a do_rtws_sync() function that does synchronous
grace-period testing, but also testing the polled API 25% of the time
each for the normal and full-state variants of the polled API.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcutorture.c

@@ -1207,6 +1207,40 @@ static void rcu_torture_write_types(void)
 	}
 }
 
+/*
+ * Do the specified rcu_torture_writer() synchronous grace period,
+ * while also testing out the polled APIs.  Note well that the single-CPU
+ * grace-period optimizations must be accounted for.
+ */
+static void do_rtws_sync(struct torture_random_state *trsp, void (*sync)(void))
+{
+	unsigned long cookie;
+	struct rcu_gp_oldstate cookie_full;
+	bool dopoll;
+	bool dopoll_full;
+	unsigned long r = torture_random(trsp);
+
+	dopoll = cur_ops->get_gp_state && cur_ops->poll_gp_state && !(r & 0x300);
+	dopoll_full = cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full && !(r & 0xc00);
+	if (dopoll || dopoll_full)
+		cpus_read_lock();
+	if (dopoll)
+		cookie = cur_ops->get_gp_state();
+	if (dopoll_full)
+		cur_ops->get_gp_state_full(&cookie_full);
+	if (dopoll || (!IS_ENABLED(CONFIG_TINY_RCU) && dopoll_full && num_online_cpus() <= 1))
+		sync();
+	sync();
+	WARN_ONCE(dopoll && !cur_ops->poll_gp_state(cookie),
+		  "%s: Cookie check 3 failed %pS() online %*pbl.",
+		  __func__, sync, cpumask_pr_args(cpu_online_mask));
+	WARN_ONCE(dopoll_full && !cur_ops->poll_gp_state_full(&cookie_full),
+		  "%s: Cookie check 4 failed %pS() online %*pbl",
+		  __func__, sync, cpumask_pr_args(cpu_online_mask));
+	if (dopoll || dopoll_full)
+		cpus_read_unlock();
+}
+
 /*
  * RCU torture writer kthread.  Repeatedly substitutes a new structure
  * for that pointed to by rcu_torture_current, freeing the old structure
@@ -1295,12 +1329,7 @@ rcu_torture_writer(void *arg)
 				break;
 			case RTWS_EXP_SYNC:
 				rcu_torture_writer_state = RTWS_EXP_SYNC;
-				if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
-					cur_ops->get_gp_state_full(&cookie_full);
-				cur_ops->exp_sync();
-				cur_ops->exp_sync();
-				if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
-					WARN_ON_ONCE(!cur_ops->poll_gp_state_full(&cookie_full));
+				do_rtws_sync(&rand, cur_ops->exp_sync);
 				rcu_torture_pipe_update(old_rp);
 				break;
 			case RTWS_COND_GET:
@@ -1339,12 +1368,7 @@ rcu_torture_writer(void *arg)
 				break;
 			case RTWS_SYNC:
 				rcu_torture_writer_state = RTWS_SYNC;
-				if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
-					cookie = cur_ops->get_gp_state();
-				cur_ops->sync();
-				cur_ops->sync();
-				if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
-					WARN_ON_ONCE(!cur_ops->poll_gp_state(cookie));
+				do_rtws_sync(&rand, cur_ops->sync);
 				rcu_torture_pipe_update(old_rp);
 				break;
 			default: