From: "Paul E. McKenney" <[email protected]>

[ 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" <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 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


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