Enhancement: Add tmt check for kmemleak

[sbertramrh]

We are attempting to automate testing on a debug kernel and want to incorporate triggering a kmemleak scan at the end of each test. If there is memleak detected then save the trace cat /sys/kernel/debug/kmemlek > $TMT_PLAN_DATA/some_file.log or any location tmt decides is best.

After reading about tmt.check functions I thought this would be a great next step.

So for each test, as with dmesg, we clear at the start:
echo clear > /sys/kernel/debug/kmemleak

Scan at the end:
echo scan > /sys/kernel/debug/kmemleak (should happen before capturing dmesg)

Capture contents of kmemleak as mentioned above. This file maybe empty.

See https://www.kernel.org/doc/html/latest/dev-tools/kmemleak.html

It is essential we get this process automated and this tmt module seems like the right fit for it.

cc: @thrix

[dennisbrendel]

Thanks @sbertramrh . I think this makes a lot of sense. I would like to add that before the first test execution of the selected plan there should be a scan followed by a clearing the kmleak report (or possibly store it in a special file), so that we do not include leaks from before actually running the first test.

[psss]

The check implementation handles two events: CheckEvent.BEFORE_TEST and CheckEvent.AFTER_TEST:

tmt/tmt/checks/dmesg.py

Lines 175 to 206 in 14d60dc

	@classmethod
	def before_test(
	cls,
	*,
	check: 'DmesgCheck',
	invocation: 'TestInvocation',
	environment: Optional[tmt.utils.Environment] = None,
	logger: tmt.log.Logger) -> list[CheckResult]:
	if not invocation.guest.facts.has_capability(GuestCapability.SYSLOG_ACTION_READ_ALL):
	return [CheckResult(name='dmesg', result=ResultOutcome.SKIP)]
	outcome, path = check._save_dmesg(invocation, CheckEvent.BEFORE_TEST, logger)
	return [CheckResult(name='dmesg', result=outcome, log=[path])]
	@classmethod
	def after_test(
	cls,
	*,
	check: 'DmesgCheck',
	invocation: 'TestInvocation',
	environment: Optional[tmt.utils.Environment] = None,
	logger: tmt.log.Logger) -> list[CheckResult]:
	if not invocation.guest.facts.has_capability(GuestCapability.SYSLOG_ACTION_READ_ALL):
	return [CheckResult(name='dmesg', result=ResultOutcome.SKIP)]
	if not invocation.is_guest_healthy:
	return [CheckResult(name='dmesg', result=ResultOutcome.SKIP)]
	outcome, path = check._save_dmesg(invocation, CheckEvent.AFTER_TEST, logger)
	return [CheckResult(name='dmesg', result=outcome, log=[path])]

I belive the before_test part could be used to clear the kmleak report.