On Wed, Aug 24, 2016 at 12:07:06PM -0700, Joe Perches wrote:
> 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.
Hm, can you be more specific? As far as I can tell, here's the only
possible call path to print_trace_address() and printk_stack_address():
show_trace_log_lvl()
dump_trace() // ops is print_trace_op
print_context_stack() // ops->walk_stack
print_trace_address() // ops->address
printk_stack_address()
So 'data' is a sneaky way to pass 'log_lvl' from show_trace_log_lvl() to
print_trace_address(), without dump_trace() and print_context_stack()
knowing what it is, because they're used in other places where 'data'
means something else.
--
Josh
