On Wed, Dec 20, 2023 at 10:11:51AM -0500, 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 <agord...@linux.ibm.com>
> Closes: 
> https://lore.kernel.org/live-patching/zyaimypyhxva9...@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com/
> Signed-off-by: Joe Lawrence <joe.lawre...@redhat.com>
> ---
>  .../testing/selftests/livepatch/functions.sh  | 37 +++++++++----------
>  1 file changed, 17 insertions(+), 20 deletions(-)

Acked-by: Alexander Gordeev <agord...@linux.ibm.com>

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