From: Paul E. McKenney <paulmck@kernel.org>
Date: Wed, 9 Oct 2024 18:02:51 +0000 (-0700)
Subject: refscale: Correct affinity check
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=046c06f5ba97b31da189396e922ebff3f502518e;p=users%2Fdwmw2%2Flinux.git

refscale: Correct affinity check

The current affinity check works fine until there are more reader
processes than CPUs, at which point the affinity check is looking for
non-existent CPUs.  This commit therefore applies the same modulus to
the check as is present in the set_cpus_allowed_ptr() call.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 0db9db73f57f2..25910ebe95c0f 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -829,7 +829,7 @@ repeat:
 		goto end;
 
 	// Make sure that the CPU is affinitized appropriately during testing.
-	WARN_ON_ONCE(raw_smp_processor_id() != me);
+	WARN_ON_ONCE(raw_smp_processor_id() != me % nr_cpu_ids);
 
 	WRITE_ONCE(rt->start_reader, 0);
 	if (!atomic_dec_return(&n_started))