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From: John Ogness <john.ogness@linutronix.de>
Subject: Re: [PATCH next v1 2/3] printk: remove safe buffers
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References: <20210316233326.10778-1-john.ogness@linutronix.de>
 <20210316233326.10778-3-john.ogness@linutronix.de>
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Date: Mon, 22 Mar 2021 12:16:15 +0100
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To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>, Steven Rostedt <rostedt@goodmis.org>, Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org, Michael Ellerman <mpe@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Eric Biederman <ebiederm@xmission.com>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@csgroup.eu>, Alistair Popple <alistair@popple.id.au>, Jordan Niethe <jniethe5@gmail.com>, Peter Zijlstra <peterz@infradead.org>, =?utf-8?Q?C=C3=A9dric?= Le Goater <clg@kaod.org>, Andrew Morton <akpm@linux-foundation.org>, Kees Cook <keescook@chromium.org>, Yue Hu <huyue2@yulong.com>, Alexey Kardashevskiy <aik@ozlabs.ru>, Rafael Aquini <aquini@redhat.com>, Tiezhu Yang <yangtiezhu@loongson.cn>, "Guilherme G. Piccoli" <gpiccoli@canonical.com>, "Paul E. McKenney" <paulmck@kernel.org>, linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org

On 2021-03-21, Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
>> @@ -369,7 +70,10 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
>>  	 * Use the main logbuf even in NMI. But avoid calling console
>>  	 * drivers that might have their own locks.
>>  	 */
>> -	if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK)) {
>> +	if (this_cpu_read(printk_context) &
>> +	    (PRINTK_NMI_DIRECT_CONTEXT_MASK |
>> +	     PRINTK_NMI_CONTEXT_MASK |
>> +	     PRINTK_SAFE_CONTEXT_MASK)) {
>
> Do we need printk_nmi_direct_enter/exit() and
> PRINTK_NMI_DIRECT_CONTEXT_MASK?  Seems like all printk_safe() paths
> are now DIRECT - we store messages to the prb, but don't call console
> drivers.

I was planning on waiting until the kthreads are introduced, in which
case printk_safe.c is completely removed. But I suppose I could switch
the 1 printk_nmi_direct_enter() user to printk_nmi_enter() so that
PRINTK_NMI_DIRECT_CONTEXT_MASK can be removed now. I would do this in a
4th patch of the series.

John Ogness

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