> Hi Miroslav,
>
> Maybe we should add a test to verify this new behavior? See sample
> version below (lightly tested). We can add to this one, or patch
> seperately if you prefer.
Thanks a lot, Joe. It looks nice. I'll include it in v3. One question
below.
> -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8--
>
>
> >From c8c9f22e3816ca4c90ab7e7159d2ce536eaa5fad Mon Sep 17 00:00:00 2001
> From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> Date: Mon, 14 Oct 2019 18:25:01 -0400
> Subject: [PATCH] selftests/livepatch: test interaction with ftrace_enabled
>
> Since livepatching depends upon ftrace handlers to implement "patched"
> functionality, verify that the ftrace_enabled sysctl value interacts
> with livepatch registration as expected.
>
> Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> ---
> tools/testing/selftests/livepatch/Makefile | 3 +-
> .../testing/selftests/livepatch/functions.sh | 18 +++++
> .../selftests/livepatch/test-ftrace.sh | 65 +++++++++++++++++++
> 3 files changed, 85 insertions(+), 1 deletion(-)
> create mode 100755 tools/testing/selftests/livepatch/test-ftrace.sh
>
> diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
> index fd405402c3ff..1886d9d94b88 100644
> --- a/tools/testing/selftests/livepatch/Makefile
> +++ b/tools/testing/selftests/livepatch/Makefile
> @@ -4,6 +4,7 @@ TEST_PROGS_EXTENDED := functions.sh
> TEST_PROGS := \
> test-livepatch.sh \
> test-callbacks.sh \
> - test-shadow-vars.sh
> + test-shadow-vars.sh \
> + test-ftrace.sh
>
> include ../lib.mk
> diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
> index 79b0affd21fb..556252efece0 100644
> --- a/tools/testing/selftests/livepatch/functions.sh
> +++ b/tools/testing/selftests/livepatch/functions.sh
> @@ -52,6 +52,24 @@ function set_dynamic_debug() {
> EOF
> }
>
> +function push_ftrace_enabled() {
> + FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
> +}
Shouldn't we call push_ftrace_enabled() somewhere at the beginning of the
test script? set_dynamic_debug() calls its push_dynamic_debug() directly,
but set_ftrace_enabled() is different, because it is called more than once
in the script.
One could argue that ftrace_enabled has to be true at the beginning of
testing anyway, but I think it would be cleaner. Btw, we should probably
guarantee that ftrace_enabled is true when livepatch selftests are
invoked.
> +function pop_ftrace_enabled() {
> + if [[ -n "$FTRACE_ENABLED" ]]; then
> + sysctl kernel.ftrace_enabled="$FTRACE_ENABLED"
> + fi
> +}
> +# set_ftrace_enabled() - save the current ftrace_enabled config and tweak
> +# it for the self-tests. Set a script exit trap
> +# that restores the original value.
> +function set_ftrace_enabled() {
> + local sysctl="$1"
> + trap pop_ftrace_enabled EXIT INT TERM HUP
> + result=$(sysctl kernel.ftrace_enabled="$1" 2>&1 | paste --serial --delimiters=' ')
> + echo "livepatch: $result" > /dev/kmsg
> +}
> +
> # loop_until(cmd) - loop a command until it is successful or $MAX_RETRIES,
> # sleep $RETRY_INTERVAL between attempts
> # cmd - command and its arguments to run
Miroslav
