[RFC PATCH 6/8] rcuscale: Allow rcu_scale_ops::get_gp_seq to be NULL

Boqun Feng
2025-04-14T06:01:28Z

For synchronization mechanisms similar to RCU, there could be no "grace
period" concept (e.g. hazard pointers), therefore allow
rcu_scale_ops::get_gp_seq to be a NULL pointer for these cases, and
simply treat started and finished grace period as 0.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
kernel/rcu/rcuscale.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 0f3059b1b80d..d9bff4b1928b 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -568,8 +568,10 @@ rcu_scale_writer(void *arg)
if (gp_exp) {
b_rcu_gp_test_started =
cur_ops->exp_completed() / 2;
- } else {
+ } else if (cur_ops->get_gp_seq) {
b_rcu_gp_test_started = cur_ops->get_gp_seq();
+ } else {
+ b_rcu_gp_test_started = 0;
}
}

@@ -625,9 +627,11 @@ rcu_scale_writer(void *arg)
if (gp_exp) {
b_rcu_gp_test_finished =
cur_ops->exp_completed() / 2;
- } else {
+ } else if (cur_ops->get_gp_seq) {
b_rcu_gp_test_finished =
cur_ops->get_gp_seq();
+ } else {
+ b_rcu_gp_test_finished = 0;
}
if (shutdown) {
smp_mb(); /* Assign before wake. */
--
2.47.1