linux-kernel - [PATCH 1/2] stop_machine: Remove this_cpu_ptr() from print_stop

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Message-Id: <20211217103209.1122679-2-bigeasy@linutronix.de>
Date:   Fri, 17 Dec 2021 11:32:08 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     fcarli@...il.com
Cc:     linux-kernel@...r.kernel.org,
        "Luis Claudio R . Goncalves" <lgoncalv@...hat.com>,
        stable-rt@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 1/2] stop_machine: Remove this_cpu_ptr() from print_stop_info().

This aligns the patch ("stop_machine: Add function and caller debug
info) with commit
  a8b62fd085050 ("stop_machine: Add function and caller debug info")

that was merged upstream and is slightly different.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/stop_machine.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index dbf585cf4b9f8..971d8acceaecb 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -51,7 +51,11 @@ static bool stop_machine_initialized = false;
 
 void print_stop_info(const char *log_lvl, struct task_struct *task)
 {
-	struct cpu_stopper *stopper = this_cpu_ptr(&cpu_stopper);
+	/*
+	 * If @task is a stopper task, it cannot migrate and task_cpu() is
+	 * stable.
+	 */
+	struct cpu_stopper *stopper = per_cpu_ptr(&cpu_stopper, task_cpu(task));
 
 	if (task != stopper->thread)
 		return;
-- 
2.34.1