Re: [PATCH v6 07/18] tracing/remotes: selftests: Add a test for the dmesg tracefs file
From: sashiko-bot@kernel.org
Date: 2026-08-17 14:05:15
Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [Medium] Unconditional write to the newly introduced `dmesg` tracefs file in `setup_remote()` breaks existing remote tests on older kernels lacking this feature. - [Medium] The dmesg test implicitly depends on dmesg timestamps and silently fails if they are disabled. --
--- Patch [7]: [PATCH v6 07/18] tracing/remotes: selftests: Add a test for the dmesg tracefs file ---commit f74a3f691a6b4375c6156c109a1d6336670de341 Author: Vincent Donnefort [off-list ref] tracing/remotes: selftests: Add a test for the dmesg tracefs file This commit adds a new selftest to exercise the newly introduced dmesg tracefs file. It checks the ability to turn on and off dmesg redirection.
quoted hunk ↗ jump to hunk
diff --git a/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc b/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc new file mode 100644 index 0000000000000..74f801a5e39ea --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc
[ ... ]
+ sleep 1
+ output=$(mktemp $TMPDIR/remote_test.XXXXXX)
+ dmesg | awk -v ts=$last_ts '
+ /^\[ *[0-9]+\.[0-9]+\]/ {
+ t=$0; sub(/^\[[ \t]*/, "", t); sub(/].*/, "", t);
+ if (t+0 > ts+0) print $0
+ }' | grep "selftest id=" | sed 's/^[^]]*] //'> $output[Severity: Medium] Does this implicitly depend on dmesg timestamps being enabled? If the kernel is configured with CONFIG_PRINTK_TIME=n, or if the user-space dmesg utility suppresses timestamps by default, the output won't have the [ X.Y] prefix. The awk script strictly expects this format and drops lines that do not match the prefix. This would result in an empty temporary file. Because the script executes with set -e, an empty file might cause the subsequent check_trace validation to abort the test. [ ... ]
quoted hunk ↗ jump to hunk
diff --git a/tools/testing/selftests/ftrace/test.d/remotes/functions b/tools/testing/selftests/ftrace/test.d/remotes/functions index 05224fac3653d..4a14aa72fdf09 100644 --- a/tools/testing/selftests/ftrace/test.d/remotes/functions +++ b/tools/testing/selftests/ftrace/test.d/remotes/functions@@ -8,6 +8,7 @@ setup_remote() cd remotes/$name/ echo 0 > tracing_on + echo 0 > dmesg
[Severity: Medium] Will this unconditional write break existing remote tests when run on older kernels? Since this test suite frequently runs with set -e enabled in the caller scripts, if the dmesg tracefs file does not exist on an older kernel, this echo command will fail with a "No such file or directory" error and abort the script. Could we check if the dmesg file exists before attempting to write to it?
clear_trace echo 7 > buffer_size_kb echo 0 > events/enable
-- Sashiko AI review · https://sashiko.dev/#/patchset/20260817135517.3919534-1-vdonnefort@google.com?part=7