rcutorture: Allow per-RCU-flavor polled double-GP check

Only vanilla RCU needs a double grace period for its compressed
polled grace-period old-state cookie.  This commit therefore adds an
rcu_torture_ops per-flavor function ->poll_need_2gp to allow this check
to be adapted to the RCU flavor under test.  A NULL pointer for this
function says that doubled grace periods are never needed.

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

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index c3c94e343eb28576f1c6baaf39d6cdcb18cc2f72..f2564c7633a8a3e690bf11c84f2a8a73b6500f72 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -341,6 +341,7 @@ struct rcu_torture_ops {
        unsigned long (*start_gp_poll)(void);
        bool (*poll_gp_state)(unsigned long oldstate);
        bool (*poll_gp_state_full)(struct rcu_gp_oldstate *rgosp);
+       bool (*poll_need_2gp)(bool poll, bool poll_full);
        void (*cond_sync)(unsigned long oldstate);
        call_rcu_func_t call;
        void (*cb_barrier)(void);
@@ -492,6 +493,11 @@ static void rcu_sync_torture_init(void)
        INIT_LIST_HEAD(&rcu_torture_removed);
 }
 
+static bool rcu_poll_need_2gp(bool poll, bool poll_full)
+{
+       return poll || (!IS_ENABLED(CONFIG_TINY_RCU) && poll_full && num_online_cpus() <= 1);
+}
+
 static struct rcu_torture_ops rcu_ops = {
        .ttype                  = RCU_FLAVOR,
        .init                   = rcu_sync_torture_init,
@@ -511,6 +517,7 @@ static struct rcu_torture_ops rcu_ops = {
        .start_gp_poll          = start_poll_synchronize_rcu,
        .poll_gp_state          = poll_state_synchronize_rcu,
        .poll_gp_state_full     = poll_state_synchronize_rcu_full,
+       .poll_need_2gp          = rcu_poll_need_2gp,
        .cond_sync              = cond_synchronize_rcu,
        .get_gp_state_exp       = get_state_synchronize_rcu,
        .start_gp_poll_exp      = start_poll_synchronize_rcu_expedited,
@@ -1228,7 +1235,7 @@ static void do_rtws_sync(struct torture_random_state *trsp, void (*sync)(void))
                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))
+       if (cur_ops->poll_need_2gp && cur_ops->poll_need_2gp(dopoll, dopoll_full))
                sync();
        sync();
        WARN_ONCE(dopoll && !cur_ops->poll_gp_state(cookie),