Re: [RFC 2/2] printk: Add more information about the printk caller

From: Petr Mladek <pmladek@suse.com>
To: "Ahmed S. Darwish" <a.darwish@linutronix.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	John Ogness <john.ogness@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Prarit Bhargava <prarit@redhat.com>,
	Mark Salyzyn <salyzyn@android.com>,
	Chunyan Zhang <zhang.lyra@gmail.com>,
	Orson Zhai <orsonzhai@gmail.com>,
	Changki Kim <changki.kim@samsung.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC 2/2] printk: Add more information about the printk caller
Date: Thu, 24 Sep 2020 14:53:01 +0200	[thread overview]
Message-ID: <20200924125259.GC29288@alley> (raw)
In-Reply-To: <20200924042414.GA6039@lx-t490>

On Thu 2020-09-24 06:24:14, Ahmed S. Darwish wrote:
> On Wed, Sep 23, 2020 at 03:56:17PM +0200, Petr Mladek wrote:
> ...
> >
> > -static inline u32 printk_caller_id(void)
> > +static enum printk_caller_ctx get_printk_caller_ctx(void)
> > +{
> > +	if (in_nmi())
> > +		return printk_ctx_nmi;
> > +
> > +	if (in_irq())
> > +		return printk_ctx_hardirq;
> > +
> > +	if (in_softirq())
> > +		return printk_ctx_softirq;
> > +
> > +	return printk_ctx_task;
> > +}
> > +
> 
> in_softirq() here will be true for both softirq contexts *and*
> BH-disabled regions. Did you mean in_serving_softirq() instead?

Good question!

I am not sure if people would want to distinguish these two
situations.

Otherwise, I think that is_softirq() more close to the meaning of
in_irq(). They both describe a context where a new interrupt has
to wait until the handling gets enabled again.

Best Regards,
Petr