linux-kernel - Re: [RFC v4 08/17] kunit: test: add support for test abort

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Date:   Tue, 19 Feb 2019 19:39:19 -0800
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Kees Cook <keescook@...gle.com>,
        Luis Chamberlain <mcgrof@...nel.org>, shuah@...nel.org,
        Rob Herring <robh@...nel.org>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Joel Stanley <joel@....id.au>,
        Michael Ellerman <mpe@...erman.id.au>,
        Joe Perches <joe@...ches.com>, brakmo@...com,
        Steven Rostedt <rostedt@...dmis.org>,
        "Bird, Timothy" <Tim.Bird@...y.com>,
        Kevin Hilman <khilman@...libre.com>,
        Julia Lawall <julia.lawall@...6.fr>,
        linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        linux-um@...ts.infradead.org, Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Knut Omang <knut.omang@...cle.com>,
        devicetree <devicetree@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        Amir Goldstein <amir73il@...il.com>, dan.carpenter@...cle.com,
        wfg@...ux.intel.com
Subject: Re: [RFC v4 08/17] kunit: test: add support for test abort

On Mon, Feb 18, 2019 at 11:52 AM Frank Rowand <frowand.list@...il.com> wrote:
>
> On 2/14/19 1:37 PM, Brendan Higgins wrote:
> > Add support for aborting/bailing out of test cases. Needed for
> > implementing assertions.
> >
> > Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
> > ---
> > Changes Since Last Version
> >  - This patch is new introducing a new cross-architecture way to abort
> >    out of a test case (needed for KUNIT_ASSERT_*, see next patch for
> >    details).
> >  - On a side note, this is not a complete replacement for the UML abort
> >    mechanism, but covers the majority of necessary functionality. UML
> >    architecture specific featurs have been dropped from the initial
> >    patchset.
> > ---
> >  include/kunit/test.h |  24 +++++
> >  kunit/Makefile       |   3 +-
> >  kunit/test-test.c    | 127 ++++++++++++++++++++++++++
> >  kunit/test.c         | 208 +++++++++++++++++++++++++++++++++++++++++--
> >  4 files changed, 353 insertions(+), 9 deletions(-)
> >  create mode 100644 kunit/test-test.c
>
> < snip >
>
> > diff --git a/kunit/test.c b/kunit/test.c
> > index d18c50d5ed671..6e5244642ab07 100644
> > --- a/kunit/test.c
> > +++ b/kunit/test.c
> > @@ -6,9 +6,9 @@
> >   * Author: Brendan Higgins <brendanhiggins@...gle.com>
> >   */
> >
> > -#include <linux/sched.h>
> >  #include <linux/sched/debug.h>
> > -#include <os.h>
> > +#include <linux/completion.h>
> > +#include <linux/kthread.h>
> >  #include <kunit/test.h>
> >
> >  static bool kunit_get_success(struct kunit *test)
> > @@ -32,6 +32,27 @@ static void kunit_set_success(struct kunit *test, bool success)
> >       spin_unlock_irqrestore(&test->lock, flags);
> >  }
> >
> > +static bool kunit_get_death_test(struct kunit *test)
> > +{
> > +     unsigned long flags;
> > +     bool death_test;
> > +
> > +     spin_lock_irqsave(&test->lock, flags);
> > +     death_test = test->death_test;
> > +     spin_unlock_irqrestore(&test->lock, flags);
> > +
> > +     return death_test;
> > +}
> > +
> > +static void kunit_set_death_test(struct kunit *test, bool death_test)
> > +{
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&test->lock, flags);
> > +     test->death_test = death_test;
> > +     spin_unlock_irqrestore(&test->lock, flags);
> > +}
> > +
> >  static int kunit_vprintk_emit(const struct kunit *test,
> >                             int level,
> >                             const char *fmt,
> > @@ -70,13 +91,29 @@ static void kunit_fail(struct kunit *test, struct kunit_stream *stream)
> >       stream->commit(stream);
> >  }
> >
> > +static void __noreturn kunit_abort(struct kunit *test)
> > +{
> > +     kunit_set_death_test(test, true);
> > +
> > +     test->try_catch.throw(&test->try_catch);
> > +
> > +     /*
> > +      * Throw could not abort from test.
> > +      */
> > +     kunit_err(test, "Throw could not abort from test!");
> > +     show_stack(NULL, NULL);
> > +     BUG();
>
> kunit_abort() is what will be call as the result of an assert failure.

Yep. Does that need clarified somewhere?

>
> BUG(), which is a panic, which is crashing the system is not acceptable
> in the Linux kernel.  You will just annoy Linus if you submit this.

Sorry, I thought this was an acceptable use case since, a) this should
never be compiled in a production kernel, b) we are in a pretty bad,
unpredictable state if we get here and keep going. I think you might
have said elsewhere that you think "a" is not valid? In any case, I
can replace this with a WARN, would that be acceptable?