[PATCH rcu 06/11] rcuscale: Provide clear error when async specified without primitives

From: Paul E. McKenney
Date: Thu Aug 01 2024 - 20:44:41 EST


Currently, if the rcuscale module's async module parameter is specified
for RCU implementations that do not have sync primitives such as
call_rcu(), there will be a series of splats due to calls to a NULL
pointer. This commit therefore warns of this situation, but switches
to non-async testing.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/rcuscale.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 933014b381ec0..315ced63ec105 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -525,7 +525,7 @@ rcu_scale_writer(void *arg)
schedule_timeout_idle(torture_random(&tr) % writer_holdoff_jiffies + 1);
wdp = &wdpp[i];
*wdp = ktime_get_mono_fast_ns();
- if (gp_async) {
+ if (gp_async && !WARN_ON_ONCE(!cur_ops->async)) {
retry:
if (!rhp)
rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
@@ -597,7 +597,7 @@ rcu_scale_writer(void *arg)
i++;
rcu_scale_wait_shutdown();
} while (!torture_must_stop());
- if (gp_async) {
+ if (gp_async && cur_ops->async) {
cur_ops->gp_barrier();
}
writer_n_durations[me] = i_max + 1;
--
2.40.1