On Thu, Feb 20, 2025 at 09:31:41AM +0100, Greg KH wrote: > On Fri, Jan 24, 2025 at 11:45:14PM -0700, Jim Cromie wrote: > > This series fixes dynamic-debug's support for DRM debug-categories. > > Classmaps-v1 evaded full review, and got committed in 2 chunks: > > > > b7b4eebdba7b..6ea3bf466ac6 # core dyndbg changes > > 0406faf25fb1..ee7d633f2dfb # drm adoption > > > > DRM-CI found a regression during init with drm.debug=<initval>; the > > static-keys under the drm-dbgs in drm.ko got enabled, but those in > > drivers & helpers did not. > > > > Root Problem: > > > > DECLARE_DYNDBG_CLASSMAP violated a K&R rule "define once, refer > > afterwards". Replace it with DYNDBG_CLASSMAP_DEFINE (invoked once in > > drm-core) and DYNDBG_CLASSMAP_USE (invoked repeatedly, in drivers & > > helpers). > > > > _DEFINE exports the classmap it creates (in drm.ko), other modules > > _USE the classmap. The _USE adds a record ref'g the _DEFINEd (& > > exported) classmap, in a 2nd __dyndbg_class_users section. > > > > So now at modprobe, dyndbg scans the new section after the 1st > > __dyndbg_class_maps section, follows the linkage to the _DEFINEr > > module, finds the (optional) kernel-param controlling the classmap, > > examines its drm.debug=<initval>, and applies it to the module being > > initialized. > > > > To recapitulate the multi-module problem wo DRM involvement, Add: > > > > A. tools/testing/selftests/dynamic_debug/* > > > > This alters pr_debugs in the test-modules, counts the results and > > checks them against expectations. It uses this formula to test most > > of the control grammar, including the new class keyword. > > > > B. test_dynamic_debug_submod.ko > > > > This alters the test-module to build both parent & _submod ko's, with > > _DEFINE and _USE inside #if/#else blocks. This recap's DRM's 2 module > > failure scenario, allowing A to exersize several cases. > > > > The #if/#else puts the 2 macro uses together for clarity, and gives > > the 2 modules identical sets of debugs. > > > > Recent DRM-CI tests are here: > > https://patchwork.freedesktop.org/series/139147/ > > > > Previous rev: > > https://lore.kernel.org/lkml/20240716185806.1572048-1-jim.cromie@xxxxxxxxx/ > > > > Noteworthy Additions: > > > > 1- drop class "protection" special case, per JBaron's preference. > > only current use is marked BROKEN so nobody to affect. > > now framed as policy-choice: > > #define ddebug_client_module_protects_classes() false > > subsystems wanting protection can change this. > > > > 2- compile-time arg-tests in DYNDBG_CLASSMAP_DEFINE > > implement several required constraints, and fail obviously. > > > > 3- modprobe time check of conflicting class-id reservations > > only affects 2+classmaps users. > > compile-time solution not apparent. > > > > 4- dyndbg can now cause modprobe to fail. > > needed to catch 3. > > maybe some loose ends here on failure. > > > > 5- refactor & rename ddebug_attach_*module_classes > > reduce repetetive boilerplate on 2 types: maps, users. > > rework mostly brought forward in patchset to reduce churn > > TBD: maybe squash more. > > > > Several recent trybot submissions (against drm-tip) have been passing > > CI.BAT, and failing one or few CI.IGT tests randomly; re-tests do not > > reliably repeat the failures. > > > > its also at github.com:jimc/linux.git > > dd-fix-9[st]-ontip & dd-fix-9-13 > > > > Ive been running it on my desktop w/o issues. > > > > The drivers/gpu/drm patches are RFC, I think there might be a single > > place to call DRM_CLASSMAP_USE(drm_dedbug_classes) to replace the > > sprinkling of _USEs in drivers and helpers. IIRC, I tried adding a > > _DEFINE into drm_drv.c, that didn't do it, so I punted for now. > > > > I think the dyndbg core additions are ready for review and merging > > into a (next-next) test/integration tree. > > So whose tree should this go through? I'm trying to get some drm folks to review/test this, but thus far not much success :-/ I think it's good stuff, but I'm somewhat hesitant if no one else agrees that it's useful for CI or in-field crash-recording or whatever ... I guess worst case we can land it and hope it attracts more folks? Wrt tree I don't care, but I guess we should then also land the drm side too. -Sima > And I think the last patch in this series isn't correct, it looks like a > 000 email somehow. > > thanks, > > greg k-h -- Simona Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
