[PATCH 3/3] kselftest: devices: Add test to detect device error logs

[Nícolas F. R. A. Prado]

Log errors are the most widely used mechanism for reporting issues in
the kernel. When an error is logged using the device helpers, eg
dev_err(), it gets metadata attached that identifies the subsystem and
device where the message is coming from. Introduce a new test that makes
use of that metadata to report which devices logged errors (or more
critical messages).

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
---
 tools/testing/selftests/Makefile                   |  1 +
 .../testing/selftests/devices/error_logs/Makefile  |  3 +
 .../devices/error_logs/test_device_error_logs.py   | 85 ++++++++++++++++++++++
 3 files changed, 89 insertions(+)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index a07ef1f473b3..e74da5e6e499 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -13,6 +13,7 @@ TARGETS += core
 TARGETS += cpufreq
 TARGETS += cpu-hotplug
 TARGETS += damon
+TARGETS += devices/error_logs
 TARGETS += devices/probe
 TARGETS += dmabuf-heaps
 TARGETS += drivers/dma-buf
diff --git a/tools/testing/selftests/devices/error_logs/Makefile b/tools/testing/selftests/devices/error_logs/Makefile
new file mode 100644
index 000000000000..d546c3fb0a7f
--- /dev/null
+++ b/tools/testing/selftests/devices/error_logs/Makefile
@@ -0,0 +1,3 @@
+TEST_PROGS := test_device_error_logs.py
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/devices/error_logs/test_device_error_logs.py b/tools/testing/selftests/devices/error_logs/test_device_error_logs.py
new file mode 100755
index 000000000000..3dd56c8ec92c
--- /dev/null
+++ b/tools/testing/selftests/devices/error_logs/test_device_error_logs.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2024 Collabora Ltd
+#
+# This test checks for the presence of error (or more critical) log messages
+# coming from devices in the kernel log.
+#
+# One failed test case is reported for each device that has outputted error
+# logs. Devices with no errors do not produce a passing test case to avoid
+# polluting the results, therefore a successful run will list 0 tests run.
+#
+
+import glob
+import os
+import re
+import sys
+
+# Allow ksft module to be imported from different directory
+this_dir = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(this_dir, "../../kselftest/"))
+
+import ksft
+
+kmsg = "/dev/kmsg"
+
+RE_log = re.compile(
+    r"(?P<prefix>[0-9]+),(?P<sequence>[0-9]+),(?P<timestamp>[0-9]+),(?P<flag>[^;]*)(,[^;]*)*;(?P<message>.*)"
+)
+RE_tag = re.compile(r" (?P<key>[^=]+)=(?P<value>.*)")
+
+PREFIX_ERROR = 3
+
+logs = []
+error_log_per_device = {}
+
+
+def parse_kmsg():
+    current_log = {}
+
+    with open(kmsg) as f:
+        os.set_blocking(f.fileno(), False)
+
+        for line in f:
+            tag_line = RE_tag.match(line)
+            log_line = RE_log.match(line)
+
+            if log_line:
+                if current_log:
+                    logs.append(current_log)  # Save last log
+
+                current_log = {
+                    "prefix": int(log_line.group("prefix")),
+                    "sequence": int(log_line.group("sequence")),
+                    "timestamp": int(log_line.group("timestamp")),
+                    "flag": log_line.group("flag"),
+                    "message": log_line.group("message"),
+                }
+            elif tag_line:
+                current_log[tag_line.group("key")] = tag_line.group("value")
+
+
+def generate_per_device_error_log():
+    for log in logs:
+        if log.get("DEVICE") and log["prefix"] <= PREFIX_ERROR:
+            if not error_log_per_device.get(log["DEVICE"]):
+                error_log_per_device[log["DEVICE"]] = []
+            error_log_per_device[log["DEVICE"]].append(log)
+
+
+parse_kmsg()
+
+generate_per_device_error_log()
+num_tests = len(error_log_per_device)
+
+ksft.print_header()
+ksft.set_plan(num_tests)
+
+for device in error_log_per_device:
+    for log in error_log_per_device[device]:
+        ksft.print_msg(log["message"])
+    ksft.test_result_fail(device)
+if num_tests == 0:
+    ksft.print_msg("No device error logs found")
+ksft.finished()

-- 
2.44.0