linux-kernel - [PATCH printk v1 15/18] printk: nobkl: Stop threads on shutdown/reboot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230302195618.156940-16-john.ogness@linutronix.de>
Date:   Thu,  2 Mar 2023 21:02:15 +0106
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
Subject: [PATCH printk v1 15/18] printk: nobkl: Stop threads on shutdown/reboot

Register a syscore_ops shutdown function to stop all threaded
printers on shutdown/reboot. This allows printk to transition back
to atomic printing in order to provide a robust mechanism for
outputting the final messages.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 kernel/printk/printk_nobkl.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/kernel/printk/printk_nobkl.c b/kernel/printk/printk_nobkl.c
index 001a1ca9793f..53989c8f1dbc 100644
--- a/kernel/printk/printk_nobkl.c
+++ b/kernel/printk/printk_nobkl.c
@@ -7,6 +7,7 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/slab.h>
+#include <linux/syscore_ops.h>
 #include "printk_ringbuffer.h"
 #include "internal.h"
 /*
@@ -1763,3 +1764,33 @@ void cons_nobkl_cleanup(struct console *con)
 	cons_state_set(con, CON_STATE_REQ, &state);
 	cons_free_percpu_data(con);
 }
+
+/**
+ * printk_kthread_shutdown - shutdown all threaded printers
+ *
+ * On system shutdown all threaded printers are stopped. This allows printk
+ * to transition back to atomic printing, thus providing a robust mechanism
+ * for the final shutdown/reboot messages to be output.
+ */
+static void printk_kthread_shutdown(void)
+{
+	struct console *con;
+
+	console_list_lock();
+	for_each_console(con) {
+		if (con->flags & CON_NO_BKL)
+			cons_kthread_stop(con);
+	}
+	console_list_unlock();
+}
+
+static struct syscore_ops printk_syscore_ops = {
+	.shutdown = printk_kthread_shutdown,
+};
+
+static int __init printk_init_ops(void)
+{
+	register_syscore_ops(&printk_syscore_ops);
+	return 0;
+}
+device_initcall(printk_init_ops);
-- 
2.30.2