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@xxxxxxxxxxxxx> > Closes: https://lore.kernel.org/live-patching/ZYAimyPYhxVA9wKg@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> Acked-by: Miroslav Benes <mbenes@xxxxxxx> M
