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(-)