calling out some thinkos

On Thu, Jun 11, 2020 at 3:19 PM [off-list ref] wrote:

heres what I have in mind.  whats described here is working.
I'll send it out soon

commit 20298ec88cc2ed64269c8be7b287a24e60a5347e
Author: Jim Cromie [off-list ref]
Date:   Wed Jun 10 12:55:08 2020 -0600

    dyndbg: WIP towards module->debugflags based callsite controls

    There are *lots* of ad-hoc debug printing solutions in kernel,
    this is a 1st attempt at providing a common mechanism for many of them.

    Basically, there are 2 styles of debug printing:
    - levels, with increasing verbosity, 1-10 forex
    - bits/flags, independently controlling separate groups of dprints

    This patch does bits/flags (with no distinction made yet between 2)

    API:

    - change pr_debug(...)  -->  pr_debug_typed(type_id=0, ...)

pr_debug, pr_debug_n now in printk.h

_?_?dynamic_.+_cl  adaptations in dynamic_debug.h

    - all existing uses have type_id=0
    - developer creates exclusive types of log messages with type_id>0
      1, 2, 3 are disjoint groups, for example: hi, mid, low

    - !!type_id is just an additional callsite selection criterion

      Qfoo() { echo module foo $* >/proc/dynamic_debug/control }
      Qfoo +p               # all groups, including default 0
      Qfoo mflags 1 +p      # only group 1
      Qfoo mflags 12 +p     # TBD[1]: groups 1 or 2
      Qfoo mflags 0 +p      # ignored atm TBD[2]
      Qfoo mflags af +p     # TBD[3]: groups a or f (10 or 15)

    so patch does:

    - add u32 debugflags to struct module. Each bit is a separate print-class.

this is feeling wrong now.
setting these bits would have to trigger an update via ddebug_exec_query
kinda like setting a bit would trigger
       echo module $foo mflags $bitpos +p > control

its possible, but not 1st, or 2nd perhaps.
In general Im quite leery of rigging up some callback to do it.

its prudent to effect all debug changes via >control

    - in ddebug_change()
      filter on !! module->debugflags,
      IFF query->module is given, and matches dt->mod_name
      and query->mflags is given, and bitmatches module->debugflags

wrong, ddebug_change cannot respond to changes of debugflags,
most it could do is consult it on queries

    - in parse_query()
      accept new query term: mflags $arg
      populate query->mflags
      arg-type needs some attention, but basic plumbing is there

    WIP: not included:

    - pr_debug_typed( bitpos=0, ....)'

now done, as pr_debug_n, pr_debug in printk.h

Ive adapted the macros with a "_cl(cl, " insertion,

also added trailing prcls to control output

    - no way to exersize new code in ddebug_change
      need pr_debug_typed() to make a (not-null) typed callsite.
      also no way to set module->debugflags

close enough to see the thinkos