Re: [PATCH v2 03/28] vsprintf: %pf(%p)

[Michal Hocko]

On Thu 19-05-22 13:23:56, Kent Overstreet wrote:
[...]
> The goal is to replace most of our %p format extensions with this
> interface, and to move pretty-printers out of the core vsprintf.c code -
> this will get us better organization and better discoverability (you'll
> be able to cscope to pretty printer calls!), as well as eliminate a lot
> of dispatch code in vsprintf.c.

Is this really something that we want? While I do see arguments about
our existing %p$FOO mess there is at least one good argument to have all
those "pretty printers" at a single location. That approach allows to do
a proper review whether those printers are safe from the printk point of
view. If we allow any random callback to be called from the printk
context we just give a free ticket to anybody to do whatever from there
without understanding of all potential consequences. 

Maybe that is less of a concern these days when printk locking has been
reworked a lot but I still do remember how frustrating it is to debug
issues related to printk getting stuck...
-- 
Michal Hocko
SUSE Labs