linux-kernel - Re: [PATCH 3/6] x86/dumpstack: make printk_stack

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Date:   Wed, 24 Aug 2016 12:07:06 -0700
From:   Joe Perches <joe@...ches.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Byungchul Park <byungchul.park@....com>,
        Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH 3/6] x86/dumpstack: make printk_stack_address() more
 generally useful

On Wed, 2016-08-24 at 13:43 -0500, Josh Poimboeuf wrote:
> On Wed, Aug 24, 2016 at 10:28:38AM -0700, Joe Perches wrote:
> > On Wed, 2016-08-24 at 11:50 -0500, Josh Poimboeuf wrote:
> > > Change printk_stack_address() to be useful when called by an unwinder
> > > outside the context of dump_trace().
> > > 
> > > Specifically:
> > > 
> > > - printk_stack_address()'s 'data' argument is always used as the log
> > >   level string.  Make that explicit.
[]
> > If this is true, and I'm not sure it is as I believe
> > there are static strings emitted like EOE and IRQ,
> > shouldn't this bubble up through the calling tree?

> []
> This function needs to keep its 'void *data' argument because it's a
> callback for stacktrace_ops, so it has to conform to the callback
> interface.  'data' is used for passing a pointer to an opaque data
> structure to the callback.
> 
> Also this is the only caller of printk_stack_address(), so there's
> nowhere else to bubble it up to.

And that shows that print_stack_address(data is not always a log level.
ie: walk_stack uses it to print a string not a log level.