linux-kernel - Re: [PATCH v3 2/3] printk: console_flush_one

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Message-ID: <873479daeh.fsf@jogness.linutronix.de>
Date: Thu, 23 Oct 2025 15:24:14 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Andrew Murray <amurray@...goodpenguin.co.uk>, Petr Mladek
 <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, Sergey
 Senozhatsky <senozhatsky@...omium.org>
Cc: linux-kernel@...r.kernel.org, Andrew Murray <amurray@...goodpenguin.co.uk>
Subject: Re: [PATCH v3 2/3] printk: console_flush_one_record() code cleanup

On 2025-10-20, Andrew Murray <amurray@...goodpenguin.co.uk> wrote:
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 1c048c66d09919967e57326e1732bd17c10f3c76..6c846d2d37d9d20bad58c6e3a7caada3be9552ca 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -3142,31 +3142,33 @@ static inline void printk_kthreads_check_locked(void) { }
>   * context.
>   *
>   * @next_seq is set to the sequence number after the last available record.
> - * The value is valid only when there is at least one usable console and all
> - * usable consoles were flushed.
> + * The value is valid only when all usable consoles were flushed. It is
> + * when the function returns true (can do the job) and @try_again parameter
> + * is set to false, see below.
>   *
>   * @handover will be set to true if a printk waiter has taken over the
>   * console_lock, in which case the caller is no longer holding the
>   * console_lock. Otherwise it is set to false.
>   *
> - * @any_usable will be set to true if there are any usable consoles.
> + * @try_again will be set to true when it still makes sense to call this
> + * function again. The function could do the job, see the return value.
> + * And some consoles still make progress.
>   *
> - * Returns true when there was at least one usable console and a record was
> - * flushed. A returned false indicates there were no records to flush for any
> - * of the consoles. It may also indicate that there were no usable consoles,
> - * the context has been lost or there is a panic suitation. Regardless the
> - * reason, the caller should assume it is not useful to immediately try again.
> + * Returns true when the function could do the job. Some consoles are usable,
> + * and there was no takeover and no panic_on_other_cpu().
>   *
>   * Requires the console_lock.
>   */
>  static bool console_flush_one_record(bool do_cond_resched, u64 *next_seq, bool *handover,
> -				     bool *any_usable)
> +				     bool *try_again)
>  {
>  	struct console_flush_type ft;
> -	bool any_progress = false;
> +	int any_usable = false;

Nit: This should be a bool.

With the change:

Reviewed-by: John Ogness <john.ogness@...utronix.de>