On Wed, 20 Dec 2023, Joe Lawrence wrote:
The livepatching kselftests rely on comparing expected vs. observed dmesg output. After each test, new dmesg entries are determined by the 'comm' utility comparing a saved, pre-test copy of dmesg to post-test dmesg output.
Alexander reports that the 'comm --nocheck-order -13' invocation used by the tests can be confused when dmesg entry timestamps vary in magnitude (ie, "[ 98.820331]" vs. "[ 100.031067]"), in which case, additional messages are reported as new. The unexpected entries then spoil the test results.
Instead of relying on 'comm' or 'diff' to determine new testing dmesg entries, refactor the code:
- pre-test : log a unique canary dmesg entry
- test : run tests, log messages
- post-test : filter dmesg starting from pre-test message
Reported-by: Alexander Gordeev agordeev@linux.ibm.com Closes: https://lore.kernel.org/live-patching/ZYAimyPYhxVA9wKg@li-008a6a4c-3549-11b2... Signed-off-by: Joe Lawrence joe.lawrence@redhat.com
Acked-by: Miroslav Benes mbenes@suse.cz
M