On Fri 2020-07-10 10:40:43, Kamalesh Babulal wrote:
> With procfs v3.3.16, the sysctl command doesn't prints the set key and
> value on error. This change breaks livepatch selftest test-ftrace.sh,
> that tests the interaction of sysctl ftrace_enabled:
>
> # selftests: livepatch: test-ftrace.sh
> # TEST: livepatch interaction with ftrace_enabled sysctl ... not ok
> #
> # --- expected
> # +++ result
> # @@ -16,7 +16,7 @@ livepatch: 'test_klp_livepatch': initial
> # livepatch: 'test_klp_livepatch': starting patching transition
> # livepatch: 'test_klp_livepatch': completing patching transition
> # livepatch: 'test_klp_livepatch': patching complete
> # -livepatch: sysctl: setting key "kernel.ftrace_enabled": Device or
> resource busy kernel.ftrace_enabled = 0
> # +livepatch: sysctl: setting key "kernel.ftrace_enabled": Device or
> resource busy
> # % echo 0 > /sys/kernel/livepatch/test_klp_livepatch/enabled
> # livepatch: 'test_klp_livepatch': initializing unpatching transition
> # livepatch: 'test_klp_livepatch': starting unpatching transition
> #
> # ERROR: livepatch kselftest(s) failed
>
> on setting sysctl kernel.ftrace_enabled={0,1} value successfully, the
> set key and value is displayed.
>
> This patch fixes it by limiting the output from both the cases to eight
> words, that includes the error message or set key and value on failure
> and success. The upper bound of eight words is enough to display the
> only tracked error message. Also, adjust the check_result string in
> test-ftrace.sh to match the expected output.
This looks really tricky.
I wonder if we could use "sysctl -q" to refuse printing the value
even with older versions. The following patch works here with
sysctl 3.3.15:
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 2aab9791791d..47aa4c762bb4 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -64,7 +64,8 @@ function set_dynamic_debug() {
}
function set_ftrace_enabled() {
- result=$(sysctl kernel.ftrace_enabled="$1" 2>&1 | paste --serial --delimiters=' ')
+ result=$(sysctl -q kernel.ftrace_enabled="$1" 2>&1 && \
+ sysctl kernel.ftrace_enabled 2>&1)
echo "livepatch: $result" > /dev/kmsg
}
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index e2a76887f40a..aa967c5d0558 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -53,7 +53,7 @@ livepatch: '$MOD_LIVEPATCH': initializing patching transition
livepatch: '$MOD_LIVEPATCH': starting patching transition
livepatch: '$MOD_LIVEPATCH': completing patching transition
livepatch: '$MOD_LIVEPATCH': patching complete
-livepatch: sysctl: setting key \"kernel.ftrace_enabled\": Device or resource busy kernel.ftrace_enabled = 0
+livepatch: sysctl: setting key \"kernel.ftrace_enabled\": Device or resource busy
% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
livepatch: '$MOD_LIVEPATCH': starting unpatching transition
Best Regards,
Petr
