Re: [PATCH] selftests/livepatch: wait for atomic replace to occur

[Joe Lawrence <joe.lawrence@redhat.com>]

On 8/22/24 12:34, Ryan Sullivan wrote:
> Uses 'loop_until' to wait for the atomic replace to unload all previous
> livepatches, as on some machines with a large number of CPUs there is a
> sizable delay between the atomic replace ocurring and when sysfs
> updates accordingly.
> 

Small nit: flip this around so it describes the problem first, then the
'loop_util' solution.  Also spell check "occurring" if you keep it 😄

> Signed-off-by: Ryan Sullivan <rysulliv@redhat.com>

Let's give the CKI credit for finding this:
Reported-by: CKI Project <cki-project@redhat.com>

If anyone is interested, here is the test/log link:
https://datawarehouse.cki-project.org/kcidb/tests/redhat:1413102084-x86_64-kernel_upt_28

By the way, was it easy to repro on a similar machine as the one
reported by CKI and then how did it fare with this patch in place?

> ---
>  tools/testing/selftests/livepatch/test-livepatch.sh | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
> index 65c9c058458d..bd13257bfdfe 100755
> --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> @@ -139,11 +139,8 @@ load_lp $MOD_REPLACE replace=1
>  grep 'live patched' /proc/cmdline > /dev/kmsg
>  grep 'live patched' /proc/meminfo > /dev/kmsg
>  
> -mods=(/sys/kernel/livepatch/*)
> -nmods=${#mods[@]}
> -if [ "$nmods" -ne 1 ]; then
> -	die "Expecting only one moduled listed, found $nmods"
> -fi
> +loop_until 'mods=(/sys/kernel/livepatch/*); nmods=${#mods[@]}; [[ "$nmods" -eq 1 ]]' ||
> +        die "Expecting only one moduled listed, found $nmods"
>  
>  # These modules were disabled by the atomic replace
>  for mod in $MOD_LIVEPATCH3 $MOD_LIVEPATCH2 $MOD_LIVEPATCH1; do

With commit msg additions above:

Acked-by: Joe Lawrence <joe.lawrence@redhat.com>

Thanks,

-- 
Joe