linux-kernel - Re: [PATCH v2] printk/nmi: avoid direct printk()-s from __printk_nmi

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Date:   Tue, 30 Aug 2016 15:03:15 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Petr Mladek <pmladek@...e.com>, Jan Kara <jack@...e.cz>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH v2] printk/nmi: avoid direct printk()-s from
 __printk_nmi_flush()

On Wed, 31 Aug 2016 01:13:54 +0900 Sergey Senozhatsky <sergey.senozhatsky@...il.com> wrote:

> __printk_nmi_flush() can be called from nmi_panic(), therefore it has to
> test whether it's executed in NMI context and thus must route the messages
> through deferred printk() or via direct printk().

Why?  What misbehaviour does the current code cause?

> Except for two places
> where __printk_nmi_flush() does unconditional direct printk() calls:
>  - pr_err("printk_nmi_flush: internal error ...")
>  - pr_cont("\n")
> 
> Factor out print_nmi_seq_line() parts into a new printk_nmi_flush_line()
> function, which takes care of in_nmi(), and use it in __printk_nmi_flush()
> for printing and error-reporting.