linux-kernel - [PATCH printk v2 26/38] kdb: use srcu console list iterator

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Message-Id: <20221019145600.1282823-27-john.ogness@linutronix.de>
Date:   Wed, 19 Oct 2022 17:01:48 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Aaron Tomlin <atomlin@...hat.com>,
        kgdb-bugreport@...ts.sourceforge.net
Subject: [PATCH printk v2 26/38] kdb: use srcu console list iterator

Guarantee safe iteration of the console list by using SRCU.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 kernel/debug/kdb/kdb_io.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 550fe8b456ec..5c0bd93c3574 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -545,6 +545,7 @@ static void kdb_msg_write(const char *msg, int msg_len)
 {
 	struct console *c;
 	const char *cp;
+	int cookie;
 	int len;
 
 	if (msg_len == 0)
@@ -558,7 +559,8 @@ static void kdb_msg_write(const char *msg, int msg_len)
 		cp++;
 	}
 
-	for_each_console(c) {
+	cookie = console_srcu_read_lock();
+	for_each_console_srcu(c) {
 		if (!console_is_enabled(c))
 			continue;
 		if (c == dbg_io_ops->cons)
@@ -577,6 +579,7 @@ static void kdb_msg_write(const char *msg, int msg_len)
 		--oops_in_progress;
 		touch_nmi_watchdog();
 	}
+	console_srcu_read_unlock(cookie);
 }
 
 int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
-- 
2.30.2