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From:   Stephen Brennan <stephen.s.brennan@oracle.com>
To:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Petr Mladek <pmladek@suse.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>, linux-kernel@vger.kernel.org,
        John Ogness <john.ogness@linutronix.de>
Subject: Re: [PATCH v3 1/4] printk: Add panic_in_progress helper
In-Reply-To: <20220201185802.98345-2-stephen.s.brennan@oracle.com>
References: <20220201185802.98345-1-stephen.s.brennan@oracle.com>
 <20220201185802.98345-2-stephen.s.brennan@oracle.com>
Date:   Tue, 01 Feb 2022 17:39:15 -0800
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Stephen Brennan <stephen.s.brennan@oracle.com> writes:
> This will be used help avoid deadlocks during panics. Although it would
> be better to include this in linux/panic.h, it would require that header
> to include linux/atomic.h as well. On some architectures, this results
> in a circular dependency. So instead add the helper directly to
> printk.c.
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> ---
>
> Notes:
>     v3: Move the helper into printk.c due to circular include
>     v2: Switch from macro to static inline function
>
>  kernel/printk/printk.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 57b132b658e1..b33c2861a8fc 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1762,6 +1762,11 @@ static DEFINE_RAW_SPINLOCK(console_owner_lock);
>  static struct task_struct *console_owner;
>  static bool console_waiter;
>  
> +static bool panic_in_progress(void)
> +{
> +	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
> +}
> +

Unfortunately this is defined within a (very large)
#ifdef CONFIG_PRINTK section. Thanks to the kbuild bot which will have
earned the reported-by tag on this patch :D

v4 will be tomorrow. Sorry for the noise everyone!

>  /**
>   * console_lock_spinning_enable - mark beginning of code where another
>   *	thread might safely busy wait
> -- 
> 2.30.2