On Thu, 30 Jul 2026 12:35:44 -0400 Andrey Grodzovsky <[email protected]> wrote:
> kernel.ftrace_enabled=0 is now always refused, so the old scenario > (disable, fail to load a livepatch, re-enable, load) no longer applies. > Replace it with a single check that the write is refused with the new > error, and drop the now-stale disable/reload flow. > > Assisted-by: Claude:claude-sonnet-5 > Signed-off-by: Andrey Grodzovsky <[email protected]> > --- > .../selftests/livepatch/test-ftrace.sh | 49 ++----------------- > 1 file changed, 3 insertions(+), 46 deletions(-) > > diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh > b/tools/testing/selftests/livepatch/test-ftrace.sh > index d2c3dea63104..c88f4d13a134 100755 > --- a/tools/testing/selftests/livepatch/test-ftrace.sh > +++ b/tools/testing/selftests/livepatch/test-ftrace.sh > @@ -9,56 +9,13 @@ MOD_LIVEPATCH=test_klp_livepatch > setup_config > > > -# - turn ftrace_enabled OFF and verify livepatches can't load > -# - turn ftrace_enabled ON and verify livepatch can load > -# - verify that ftrace_enabled can't be turned OFF while a livepatch is > loaded > +# - verify that kernel.ftrace_enabled=0 is refused (deprecated knob) > > -start_test "livepatch interaction with ftrace_enabled sysctl" > +start_test "ftrace_enabled sysctl write is refused (deprecated)" > > -set_ftrace_enabled 0 > -load_failing_mod $MOD_LIVEPATCH > - > -set_ftrace_enabled 1 > -load_lp $MOD_LIVEPATCH > -if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" > ]] ; then > - echo -e "FAIL\n\n" > - die "livepatch kselftest(s) failed" > -fi > - This test should work for both old and new kernels. I would have it still do everything here but if setting ftrace_enabled returns -EOPNOTSUPP then do the simple path. -- Steve > -# Check that ftrace could not get disabled when a livepatch is enabled > set_ftrace_enabled --fail 0 > -if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" > ]] ; then > - echo -e "FAIL\n\n" > - die "livepatch kselftest(s) failed" > -fi > -disable_lp $MOD_LIVEPATCH > -unload_lp $MOD_LIVEPATCH > > -check_result "livepatch: kernel.ftrace_enabled = 0 > -% insmod test_modules/$MOD_LIVEPATCH.ko > -livepatch: enabling patch '$MOD_LIVEPATCH' > -livepatch: '$MOD_LIVEPATCH': initializing patching transition > -livepatch: failed to register ftrace handler for function > 'cmdline_proc_show' (-16) > -livepatch: failed to patch object 'vmlinux' > -livepatch: failed to enable patch '$MOD_LIVEPATCH' > -livepatch: '$MOD_LIVEPATCH': canceling patching transition, going to unpatch > -livepatch: '$MOD_LIVEPATCH': completing unpatching transition > -livepatch: '$MOD_LIVEPATCH': unpatching complete > -insmod: ERROR: could not insert module test_modules/$MOD_LIVEPATCH.ko: > Device or resource busy > -livepatch: kernel.ftrace_enabled = 1 > -% insmod test_modules/$MOD_LIVEPATCH.ko > -livepatch: enabling patch '$MOD_LIVEPATCH' > -livepatch: '$MOD_LIVEPATCH': initializing patching transition > -livepatch: '$MOD_LIVEPATCH': starting patching transition > -livepatch: '$MOD_LIVEPATCH': completing patching transition > -livepatch: '$MOD_LIVEPATCH': patching complete > -livepatch: sysctl: setting key \"kernel.ftrace_enabled\": Device or resource > busy > -% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled > -livepatch: '$MOD_LIVEPATCH': initializing unpatching transition > -livepatch: '$MOD_LIVEPATCH': starting unpatching transition > -livepatch: '$MOD_LIVEPATCH': completing unpatching transition > -livepatch: '$MOD_LIVEPATCH': unpatching complete > -% rmmod $MOD_LIVEPATCH" > +check_result "livepatch: sysctl: setting key \"kernel.ftrace_enabled\": > Operation not supported" > > > # - verify livepatch can load
