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From:   John Ogness <john.ogness@linutronix.de>
To:     Petr Mladek <pmladek@suse.com>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Douglas Anderson <dianders@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org
Subject: [PATCH printk v5 35/40] tty: serial: kgdboc: use srcu console list iterator
Date:   Wed, 16 Nov 2022 17:27:47 +0106
Message-Id: <20221116162152.193147-36-john.ogness@linutronix.de>
In-Reply-To: <20221116162152.193147-1-john.ogness@linutronix.de>
References: <20221116162152.193147-1-john.ogness@linutronix.de>
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Use srcu console list iteration for safe console list traversal.
Note that this is a preparatory change for when console_lock no
longer provides synchronization for the console list.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
 drivers/tty/serial/kgdboc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 5be381003e58..c6df9ef34099 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -451,6 +451,7 @@ static void kgdboc_earlycon_pre_exp_handler(void)
 {
 	struct console *con;
 	static bool already_warned;
+	int cookie;
 
 	if (already_warned)
 		return;
@@ -463,9 +464,14 @@ static void kgdboc_earlycon_pre_exp_handler(void)
 	 * serial drivers might be OK with this, print a warning once per
 	 * boot if we detect this case.
 	 */
-	for_each_console(con)
+	cookie = console_srcu_read_lock();
+	for_each_console_srcu(con) {
 		if (con == kgdboc_earlycon_io_ops.cons)
-			return;
+			break;
+	}
+	console_srcu_read_unlock(cookie);
+	if (con)
+		return;
 
 	already_warned = true;
 	pr_warn("kgdboc_earlycon is still using bootconsole\n");
-- 
2.30.2