From f7eee341b1a1781e561d074cef0c409c8208a786 Mon Sep 17 00:00:00 2001
From: Liu Song <liu.song11@zte.com.cn>
Date: Wed, 30 Jun 2021 22:08:02 +0800
Subject: [PATCH] rcu: Use per_cpu_ptr to get the pointer of per_cpu variable

References: bnc#1189998 (PREEMPT_RT prerequisite backports)
Patch-mainline: v5.15-rc1
Git-commit: 8211e922de2854130e3633f52cd4fc2d7817ceb0

There are a few remaining locations in kernel/rcu that still use
"&per_cpu()".  This commit replaces them with "per_cpu_ptr(&)", and does
not introduce any functional change.

Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/rcu/tasks.h      | 2 +-
 kernel/rcu/tree.c       | 2 +-
 kernel/rcu/tree_stall.h | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index fd3909c59b6a..a960017680f7 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -919,7 +919,7 @@ static void trc_read_check_handler(void *t_in)
 	// Allow future IPIs to be sent on CPU and for task.
 	// Also order this IPI handler against any later manipulations of
 	// the intended task.
-	smp_store_release(&per_cpu(trc_ipi_to_cpu, smp_processor_id()), false); // ^^^
+	smp_store_release(per_cpu_ptr(&trc_ipi_to_cpu, smp_processor_id()), false); // ^^^
 	smp_store_release(&texp->trc_ipi_to_cpu, -1); // ^^^
 }
 
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 867bd3aa4666..c7a94806f442 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1286,7 +1286,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 	 */
 	jtsq = READ_ONCE(jiffies_to_sched_qs);
 	ruqp = per_cpu_ptr(&rcu_data.rcu_urgent_qs, rdp->cpu);
-	rnhqp = &per_cpu(rcu_data.rcu_need_heavy_qs, rdp->cpu);
+	rnhqp = per_cpu_ptr(&rcu_data.rcu_need_heavy_qs, rdp->cpu);
 	if (!READ_ONCE(*rnhqp) &&
 	    (time_after(jiffies, rcu_state.gp_start + jtsq * 2) ||
 	     time_after(jiffies, rcu_state.jiffies_resched) ||
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 0e7a60706d1c..6b2c5b53414e 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -354,7 +354,7 @@ static void rcu_dump_cpu_stacks(void)
 
 static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
 {
-	struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 
 	sprintf(cp, "last_accelerate: %04lx/%04lx dyntick_enabled: %d",
 		rdp->last_accelerate & 0xffff, jiffies & 0xffff,