linux-kernel - [PATCH 0/4] dyndbg: POC use dynamic_debug_exec

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Date:   Wed, 26 Aug 2020 11:00:37 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        jbaron@...mai.com
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH 0/4] dyndbg: POC use dynamic_debug_exec_queries in DRM

This patchset tests/demonstrates using dynamic_debug_exec_queries() to
alter 2 drivers' pr_debugs without a user directly using >control.

For drm.core, I copied drm.debug module parameter model, adding
drm.debug2 as a POC user interface to control 2 pr_debug additions to
drm_printk:drm_dbg,dev_dbg, allowing both category and >control to
work in parallel.  This patch makes no attempt to integrate drm's
category mechanism with the "format=^class" callsite selection; thats
the "theory", but it needs testing.

For i915/gvt, I repeated the pattern.  I focussed on gvt only, because
it had the most compelling use of format strings as pr_debug classes;
~120 pr_debugs in 9 classes.  These are mapped onto bits of the param.

bash-5.0# echo 0x0 > /sys/module/i915/parameters/debug_dyn 
[ 3137.044185] set_dyndbg: result:0x0 from 0x0
[ 3137.044185] 
[ 3137.047370] dyndbg: query 0: "format='^gvt: cmd: ' -p"
[ 3137.050302] dyndbg: entry, buf:'format='^gvt: cmd: ' -p'
[ 3137.053331] dyndbg: start-of-word:0 'format='^gvt: cmd: ' -p'

These patches were the test/use case for-59 fixes:
https://lore.kernel.org/lkml/20200825173339.2082585-1-jim.cromie@gmail.com/

Jim Cromie (4):
  drm-printk: POC caller of dynamic-debug-exec-queries
  drm-printk: call pr_debug() from drm_dev_dbg, __drm_dbg
  i915: add -DDYNAMIC_DEBUG_MODULE to i915/gvt/Makefile
  i915: POC use dynamic_debug_exec_queries to control pr_debugs in gvt

 drivers/gpu/drm/drm_print.c        | 54 ++++++++++++++++++---
 drivers/gpu/drm/i915/gvt/Makefile  |  5 +-
 drivers/gpu/drm/i915/i915_params.c | 76 ++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+), 8 deletions(-)

-- 
2.26.2