[PATCH AUTOSEL 6.11 119/244] rcuscale: Provide clear error when async specified without primitives

Sasha Levin
2024-09-25T11:42:25Z

From: "Paul E. McKenney" <paulmck@kernel.org>

[ Upstream commit 11377947b5861fa59bf77c827e1dd7c081842cc9 ]

Currently, if the rcuscale module's async module parameter is specified
for RCU implementations that do not have async primitives such as RCU
Tasks Rude (which now lacks a call_rcu_tasks_rude() function), 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@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 b53a9e8f5904f..f88c75b3cea3b 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -499,7 +499,7 @@ 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);
@@ -555,7 +555,7 @@ 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;
--
2.43.0