Subject: Re: [PATCH 00/50] Add log level to show_stack()

From: Sergey Senozhatsky <[email-masked]>
Date: Tue, 12 Nov 2019 13:25:46 +0900

On (19/11/12 02:40), Dmitry Safonov wrote:
[..]
> In my point of view the cost of one-time [mostly build] testing every
> architecture is cheaper than introducing some new smart code that will
> live forever.

Well, there may be the need to pass loglevel deeper due to "hey __show_stack()
on that arch invokes bar(), which invokes foo() and now foo() does printk(),
but we don't see it". The context which decided to backtaraces decided
to do so for a reason, probably, so I guess we can look at it as "a special
error reporting code block".

The proposed patch set passes loglevel via slightly unusual channel -
via sprintf(). We probably can do it, but I would prefer to minimize
the number of such printk-s in the kernel. The code snippet which I
posted also does pretty unusual thing w.r.t loglevel. Both approaches
are "non-standard" from that POV.

> I'll reply to your suggestion tomorrow, it's a bit late in my tz.

Sure.

To anyone who will comment on that code snippet - this is not a
"look, here is what you need to do" type of proposal. Just an
alternative approach with its pros and cons.

We had several requests over the years to have something like "forcibly
allow all underlying printk-s from here to here" or "forcibly suppress
or postpone underlying printk-s from here to here", etc.

	-ss