Re: [PATCH v2 3/4] printk: nbcon: move printk_delay to console emiting code

[John Ogness <john.ogness@linutronix.de>]

On 2026-07-07, Petr Mladek <pmladek@suse.com> wrote:
>> This is too deep (also pointed out by Sashiko) because it multiplies the
>> delay times the number of consoles. For the legacy printing, it would be
>> more appropriate to put the delay inside console_flush_all() and
>> legacy_kthread_func().
>
> True. The question is if the proper solution is worth the complexity.
> We would need to pass the information down two level of the API.
> It would require adding a new (output) parameter to console_flush_one_record(),
> nbcon_legacy_emit_next_record(), and console_emit_next_record().
>
> It is not that complicated but these functions are already hairy
> enough so we should be careful.

Fair enough. But then it should be consistent and
console_emit_next_record() should perform the delay before allowing the
handover. Something like this:

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2fe9a963c823a..62fd6a5ebef66 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3161,6 +3161,8 @@ static bool console_emit_next_record(struct console *con, bool *handover, int co
 		 */
 
 		con->write(con, outbuf, pmsg.outbuf_len);
+		printk_delay(false);
+
 		con->seq = pmsg.seq + 1;
 	} else {
 		/*
@@ -3182,6 +3184,7 @@ static bool console_emit_next_record(struct console *con, bool *handover, int co
 		printk_legacy_allow_spinlock_enter();
 		con->write(con, outbuf, pmsg.outbuf_len);
 		printk_legacy_allow_spinlock_exit();
+		printk_delay(true);
 
 		start_critical_timings();
 

John