diff mbox series

[printk,v1,15/18] printk: nobkl: Stop threads on shutdown/reboot

Message ID 20230302195618.156940-16-john.ogness@linutronix.de
State New
Headers
Series threaded/atomic console support |

Commit Message

John Ogness March 2, 2023, 7:56 p.m. UTC 
  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@linutronix.de>
---
 kernel/printk/printk_nobkl.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

Comments

Petr Mladek April 13, 2023, 9:03 a.m. UTC | #1 
On Thu 2023-03-02 21:02:15, John Ogness wrote:
> 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.
>
> --- a/kernel/printk/printk_nobkl.c
> +++ b/kernel/printk/printk_nobkl.c
> @@ -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();

It would make sense to explicitly flush the consoles after stopping
the kthreads. There might be pending messages...

> +}
> +
> +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);

Otherwise it looks good.

Best Regards,
Petr
diff mbox series

Patch

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);