linux-kernel - Re: [PATCH 2/2] selftests: kvm: replace exit() with ksft_exit_fail

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Date: Thu, 13 Jun 2024 11:57:30 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, 
	Anup Patel <anup@...infault.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, kernel@...labora.com, kvm@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] selftests: kvm: replace exit() with ksft_exit_fail_msg()

On Thu, Jun 13, 2024, Muhammad Usama Anjum wrote:
> > As above, AFAICT it comes from Google's internal test infrastructure (KVM selftests
> > came from Google).
> > 
> >> Its even better if we use ksft_exit_fail_msg() which will print out "Bail
> >> out" meaning the test exited without completing. This string is TAP protocol
> >> specific.
> > 
> > This is debatable and not obviously correct.  The documentation says:
> > 
> >   Bail out!
> >   As an emergency measure a test script can decide that further tests are
> >   useless (e.g. missing dependencies) and testing should stop immediately. In
> >   that case the test script prints the magic words
> > 
> > which suggests that a test should only emit "Bail out!" if it wants to stop
> > entirely.  We definitely don't want KVM selftests to bail out if a TEST_ASSERT()
> > fails in one testcase.
> But KVM tests are bailing out if assert fails, exit(254) is being called
> which stops the further execution of the test cases.

Not if the TEST_ASSERT() fires from within a test fixture, in which case the
magic in tools/testing/selftests/kselftest_harness.h captures the failure but
continues on with the next test.