linux-kernel - Re: [PATCH 6/7] arch: __get_wchan || STACKTRACE

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Date:   Thu, 14 Oct 2021 19:07:38 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>, keescook@...omium.org,
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Subject: Re: [PATCH 6/7] arch: __get_wchan || STACKTRACE_SUPPORT

On Fri, Oct 08, 2021 at 09:17:07AM -0700, Josh Poimboeuf wrote:
> On Fri, Oct 08, 2021 at 03:45:59PM +0200, Peter Zijlstra wrote:
> > > stack_trace_save_tsk() *shouldn't* skip anything unless we've explicitly
> > > told it to via skipnr, because I'd expect that
> > 
> > It's what most archs happen to do today and is what
> > stack_trace_save_tsk() as implemented using arch_stack_walk() does.
> > Which is I think the closest to canonical we have.

Ah; and arch_stack_walk() itself shouldn't skip anything, which gives
the consistent low-level semantic I wanted.

> It *is* confusing though.  Even if 'nosched' may be the normally
> desired behavior, stack_trace_save_tsk() should probably be named
> stack_trace_save_tsk_nosched().

I agree that'd be less confusing!

Josh, am I right in my understanding that the reliable stacktrace
functions *shouldn't* skip sched functions, or should those similarly
gain a _nosched suffix?

Thanks,
Mark.