linux-kernel - Re: [PATCH v1] kernel/printk: check return value of console

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Message-ID: <YycYDn82QQZYfpsl@google.com>
Date:   Sun, 18 Sep 2022 22:11:29 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Li Zhong <floridsleeves@...il.com>
Cc:     linux-kernel@...r.kernel.org, tony.luck@...el.com,
        ccross@...roid.com, anton@...msg.org, keescook@...omium.org,
        john.ogness@...utronix.de, rostedt@...dmis.org,
        senozhatsky@...omium.org, pmladek@...e.com
Subject: Re: [PATCH v1] kernel/printk: check return value of console_trylock()

On (22/09/16 18:58), Li Zhong wrote:
> Check the console_trylock() return value in case it fails.
[..]
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index a1a81fd9889b..2c6a0484315b 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2937,7 +2937,8 @@ void console_flush_on_panic(enum con_flush_mode mode)
>  	 * context and we don't want to get preempted while flushing,
>  	 * ensure may_schedule is cleared.
>  	 */
> -	console_trylock();
> +	if (!console_trylock())
> +		return;

It supposed to be ignored and the comment above (in the code)
explains why: this is panic flush, we want to proceed regardless.