Re: [PATCH 1/2] x86/dumpstack: Optimize save_stack_trace

[Byungchul Park <byungchul.park@lge.com>]

On Mon, Jul 18, 2016 at 08:09:10AM -0500, Josh Poimboeuf wrote:
> > > > There are several different users of save_stack_trace() in the kernel, we can't
> > > > be sure that all of them are interested in dropping those guesses.
> > > > 
> > > > So I'd rather advocate in favour of a new seperate helper.
> > > 
> > > So how about we change save_stack_trace() to use print_context_stack()
> > > for CONFIG_FRAME_POINTER=n and print_context_stack_bp() for
> > > CONFIG_FRAME_POINTER=y?  That would preserve the existing behavior, no?
> > 
> > Even if CONFIG_FRAME_POINTER=y, someone may want to guess, doesn't they?
> 
> For CONFIG_FRAME_POINTER=y, the guesses are ignored by
> __save_stack_address() and only the reliable addresses are saved.

Indeed. I was confused.

> We shouldn't change that behavior, unless you actually know of a caller
> who wants the guesses.  And even then the "guess" variation should be
> named accordingly to make it clear that it's not a "reliable" stack
> trace, even though frame pointers are enabled.

My question was caused by being confused. I agree with you.

> 
> -- 
> Josh