Re: [PATCH v3 2/2] selftests/livepatch: filter debug messages in check_result()

[Petr Mladek <pmladek@suse.com>]

On Fri 2026-08-21 11:16:48, Yafang Shao wrote:
> CONFIG_DEBUG_KOBJECT makes kobject_add_internal(), kobject_uevent_env(),
> fill_kobj_path() and friends emit pr_debug() messages, and
> CONFIG_DEBUG_KOBJECT_RELEASE makes kobject_release() emit a pr_info()
> for every delayed kobject free.  All of these carry the "kobject:" prefix
> via pr_fmt(), e.g.:
> 
>  # --- expected
>  # +++ result
>  # @@ -1,7 +1,13 @@
>  #  % insmod test_modules/test_klp_livepatch.ko
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_add_internal: parent: 'module', set: 'module'
>  # +kobject: 'holders' (000000002856f0ae): kobject_add_internal: parent: 'test_klp_livepatch', set: '<NULL>'
>  # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_add_internal: parent: 'livepatch', set: '<NULL>'
>  # +kobject: 'vmlinux' (000000007b8837e6): kobject_add_internal: parent: 'test_klp_livepatch', set: '<NULL>'
>  #  livepatch: enabling patch 'test_klp_livepatch'
>  #  livepatch: 'test_klp_livepatch': initializing patching transition
>  #  livepatch: 'test_klp_livepatch': starting patching transition
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_uevent_env
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): fill_kobj_path: path = '/module/test_klp_livepatch'
>  #  livepatch: 'test_klp_livepatch': completing patching transition
>  #  livepatch: 'test_klp_livepatch': patching complete
>  #  % echo 0 > /sys/kernel/livepatch/test_klp_livepatch/enabled
>  # @@ -9,4 +15,17 @@ livepatch: 'test_klp_livepatch': initial
>  #  livepatch: 'test_klp_livepatch': starting unpatching transition
>  #  livepatch: 'test_klp_livepatch': completing unpatching transition
>  #  livepatch: 'test_klp_livepatch': unpatching complete
>  # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_release, parent 00000000f8785d63 (delayed 2000)
>  # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_cleanup, parent 00000000f8785d63
>  # +kobject: 'test_klp_livepatch' (00000000dcae1113): auto cleanup kobject_del
>  # +kobject: 'test_klp_livepatch' (00000000dcae1113): calling ktype release
>  # +kobject: 'test_klp_livepatch': free name
>  #  % rmmod test_klp_livepatch
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_release, parent 0000000052e5c022 (delayed 3000)
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_cleanup, parent 0000000052e5c022
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): auto cleanup kobject_del
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): auto cleanup 'remove' event
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_uevent_env
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): fill_kobj_path: path = '/module/test_klp_livepatch'
>  # +kobject: 'test_klp_livepatch' (000000009dbf565e): calling ktype release
>  # +kobject: 'test_klp_livepatch': free name
>  #
>  # ERROR: livepatch kselftest(s) failed
>  not ok 1 selftests: livepatch: test-livepatch.sh # exit=1
> 
> The livepatch test modules' kobjects are named "test_klp_*", so these
> lines match the check_result() grep for "test_klp" and leak into the
> result.  The extra lines no longer match the expected output, so the
> selftests fail when either debug config is enabled.
> 
> Filtering out every "kobject:" line also hides real WARN()s, e.g. the
> one kobject_get() emits for an object whose refcount was not
> initialized.  Filtering with "dmesg --level=..." is not enough either,
> since the tests enable livepatch pr_debug() through dynamic_debug/control
> and expect its messages.  Read the log with "dmesg --raw" and drop only
> the debug-level messages without the "livepatch:" prefix, plus the
> specific delayed-release info message.
> 
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>

I am not much familiar with awk. But the changes look good
and selftests passed so:

Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr