From: Brendan Higgins <brendanhiggins@google.com>
To: Petr Mladek <pmladek@suse.com>
Cc: mcgrof@kernel.org, Greg KH <gregkh@linuxfoundation.org>,
Kees Cook <keescook@google.com>,
shuah@kernel.org, Joel Stanley <joel@jms.id.au>,
mpe@ellerman.id.au, joe@perches.com, brakmo@fb.com,
rostedt@goodmis.org, Tim.Bird@sony.com, khilman@baylibre.com,
Julia Lawall <julia.lawall@lip6.fr>,
linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
jdike@addtoit.com, richard@nod.at, linux-um@lists.infradead.org,
Daniel Vetter <daniel@ffwll.ch>,
dri-devel@lists.freedesktop.org, Rob Herring <robh@kernel.org>,
dan.j.williams@intel.com, linux-nvdimm@lists.01.org,
kieran.bingham@ideasonboard.com,
Frank Rowand <frowand.list@gmail.com>,
Knut Omang <knut.omang@oracle.com>
Subject: Re: [RFC v3 03/19] kunit: test: add string_stream a std::stream like string builder
Date: Mon, 3 Dec 2018 16:35:12 -0800 [thread overview]
Message-ID: <CAFd5g47pWbPso4LG93ffRUZjLhxnqws5VfYc5SfFf8FbuYCWvA@mail.gmail.com> (raw)
In-Reply-To: <20181203105517.vbedwygttxxbdtan@pathway.suse.cz>
On Mon, Dec 3, 2018 at 2:55 AM Petr Mladek <pmladek@suse.com> wrote:
>
> On Thu 2018-11-29 19:29:24, Luis Chamberlain wrote:
> > On Wed, Nov 28, 2018 at 11:36:20AM -0800, Brendan Higgins wrote:
> > > A number of test features need to do pretty complicated string printing
> > > where it may not be possible to rely on a single preallocated string
> > > with parameters.
> > >
> > > So provide a library for constructing the string as you go similar to
> > > C++'s std::string.
> >
> > Hrm, what's the potential for such thing actually being eventually
> > generically useful for printk folks, I wonder? Petr?
>
> printk() is a bit tricky:
>
> + It should work in any context. Any additional lock adds risk of a
> deadlock. Especially the NMI and scheduler contexts are problematic.
> There are problems with any other code that might be called
> from console drivers and calls printk() under a lock.
>
> + It should work also when the system is out of memory. Especially
> atomic context is problematic because we could not wait for
> memory reclaim or swap.
>
> + We also do to the best effort to get the message out on the
> console. It is important when the system is about to die.
> Any extra buffering layer might cause delay and avoid seeing the
> message.
>
> From this point of views, this API is not generally usable with printk().
Yeah, that makes sense. I wouldn't really expect this to work well in
those cases.
> Now, the question is how many of the above fits also for unit testing.
> At least, you might need to be careful when allocating memory in
> atomic context.
True, but this is only supposed to be used for constructing
expectation failure messages which should only happen from a
non-atomic context.
>
> BTW: There are more existing printk APIs: Well, I admit the they are
> not easily reusable in unit testing:
>
> + printk() is old, crappy code, complicated with all the
> cornercases and consoles.
>
> + include/linux/seq_buf.h is simple buffering. It is used primary
> for sysfs output. It might be usable if you add support for
> loglevel and use big enough buffer. I quess that you should
> flush the buffer regularly anyway.
>
> + trace_printk() uses lockless per-CPU buffers. It currently does not
> support loglevels. But it might be pretty interesting choice as well.
>
>
> I do not say that you have to use one of the existing API. But you
> might consider them if you encouter any problems and maintaining
> your variant gets complicated.
Alright, I will take a look.
Thanks!
next prev parent reply other threads:[~2018-12-04 0:35 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 19:36 [RFC v3 00/19] kunit: introduce KUnit, the Linux kernel unit testing framework Brendan Higgins
2018-11-28 19:36 ` [RFC v3 01/19] kunit: test: add KUnit test runner core Brendan Higgins
2018-11-30 3:14 ` Luis Chamberlain
2018-12-01 1:51 ` Brendan Higgins
2018-12-01 2:57 ` Luis Chamberlain
2018-12-05 13:15 ` Anton Ivanov
2018-12-05 14:45 ` Arnd Bergmann
2018-12-05 14:49 ` Anton Ivanov
2018-11-30 3:28 ` Luis Chamberlain
[not found] ` <20181130032802.GG18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-01 2:08 ` Brendan Higgins
2018-12-01 3:10 ` Luis Chamberlain
[not found] ` <20181201031049.GL28501-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 22:47 ` Brendan Higgins
2018-12-01 3:02 ` Luis Chamberlain
2018-11-28 19:36 ` [RFC v3 10/19] kunit: test: add test managed resource tests Brendan Higgins
[not found] ` <20181128193636.254378-1-brendanhiggins-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2018-11-28 19:36 ` [RFC v3 02/19] kunit: test: add test resource management API Brendan Higgins
2018-11-28 19:36 ` [RFC v3 03/19] kunit: test: add string_stream a std::stream like string builder Brendan Higgins
2018-11-30 3:29 ` Luis Chamberlain
2018-12-01 2:14 ` Brendan Higgins
2018-12-01 3:12 ` Luis Chamberlain
2018-12-03 10:55 ` Petr Mladek
2018-12-04 0:35 ` Brendan Higgins [this message]
2018-11-28 19:36 ` [RFC v3 04/19] kunit: test: add test_stream a std::stream like logger Brendan Higgins
2018-11-28 19:36 ` [RFC v3 05/19] kunit: test: add the concept of expectations Brendan Higgins
2018-11-28 19:36 ` [RFC v3 06/19] arch: um: enable running kunit from User Mode Linux Brendan Higgins
2018-11-28 21:26 ` Rob Herring
2018-11-30 3:37 ` Luis Chamberlain
2018-11-30 14:05 ` Rob Herring
2018-11-30 18:22 ` Luis Chamberlain
[not found] ` <20181130182203.GS18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:22 ` Brendan Higgins
2018-11-30 3:30 ` Luis Chamberlain
2018-11-28 19:36 ` [RFC v3 07/19] kunit: test: add initial tests Brendan Higgins
2018-11-30 3:40 ` Luis Chamberlain
2018-12-03 23:26 ` Brendan Higgins
2018-12-03 23:43 ` Luis Chamberlain
2018-11-28 19:36 ` [RFC v3 08/19] arch: um: add shim to trap to allow installing a fault catcher for tests Brendan Higgins
2018-11-30 3:34 ` Luis Chamberlain
[not found] ` <20181130033429.GK18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:34 ` Brendan Higgins
[not found] ` <CAFd5g45+MAVaSW8HN9x57Y8Um=TV1Oa=-K8yExPBS-4KjLyciQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-03 23:46 ` Luis Chamberlain
[not found] ` <20181203234628.GR28501-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-04 0:44 ` Brendan Higgins
2018-11-30 3:41 ` Luis Chamberlain
2018-12-03 23:37 ` Brendan Higgins
2018-11-28 19:36 ` [RFC v3 09/19] kunit: test: add the concept of assertions Brendan Higgins
2018-11-28 19:36 ` [RFC v3 11/19] kunit: add Python libraries for handing KUnit config and kernel Brendan Higgins
2018-11-29 13:54 ` Kieran Bingham
[not found] ` <841cf4ae-501b-05ae-5863-a51010709b67-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
2018-12-03 23:48 ` Brendan Higgins
2018-12-04 20:47 ` Luis Chamberlain
2018-12-06 12:32 ` Kieran Bingham
2018-12-06 15:37 ` Matthew Wilcox
2018-12-07 11:30 ` Kieran Bingham
2018-12-11 14:09 ` Petr Mladek
2018-12-11 14:41 ` Steven Rostedt
2018-12-11 17:01 ` Anton Ivanov
2019-02-09 0:40 ` Brendan Higgins
2018-12-07 1:05 ` Luis Chamberlain
2018-12-07 18:35 ` Kent Overstreet
2018-11-30 3:44 ` Luis Chamberlain
2018-12-03 23:50 ` Brendan Higgins
2018-12-04 20:48 ` Luis Chamberlain
2018-11-28 19:36 ` [RFC v3 12/19] kunit: add KUnit wrapper script and simple output parser Brendan Higgins
2018-11-28 19:36 ` [RFC v3 13/19] kunit: improve output from python wrapper Brendan Higgins
2018-11-28 19:36 ` [RFC v3 14/19] Documentation: kunit: add documentation for KUnit Brendan Higgins
2018-11-29 13:56 ` Kieran Bingham
2018-11-30 3:45 ` Luis Chamberlain
[not found] ` <20181130034525.GP18410-dAjH6bxAqesAS62YNPtMr3dQhYtBYE6JAL8bYrjMMd8@public.gmane.org>
2018-12-03 23:53 ` Brendan Higgins
2018-12-06 12:16 ` Kieran Bingham
2019-02-09 0:56 ` Brendan Higgins
2019-02-11 12:16 ` Kieran Bingham
2019-02-12 22:10 ` Brendan Higgins
2019-02-13 21:55 ` Kieran Bingham
2019-02-14 0:17 ` Brendan Higgins
2019-02-14 17:26 ` Luis Chamberlain
2019-02-14 22:07 ` Brendan Higgins
2018-11-28 19:36 ` [RFC v3 15/19] MAINTAINERS: add entry for KUnit the unit testing framework Brendan Higgins
2018-11-28 19:36 ` [RFC v3 17/19] of: unittest: migrate tests to run on KUnit Brendan Higgins
2018-11-28 20:56 ` Rob Herring
2018-11-30 0:39 ` Randy Dunlap
[not found] ` <18814973-8f0a-4647-a097-fcc3dc0b3cd3-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-12-04 0:13 ` Brendan Higgins
2018-12-04 13:40 ` Rob Herring
[not found] ` <CAL_JsqL_PivQbrJFEusdKAy-2EQtKL3OHbmyYSK9bzuTOQegqA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-05 23:42 ` Brendan Higgins
2018-12-07 0:41 ` Rob Herring
2018-12-04 0:08 ` Brendan Higgins
2019-02-13 1:44 ` Brendan Higgins
2019-02-14 20:10 ` Rob Herring
2019-02-14 21:52 ` Brendan Higgins
2019-02-18 22:56 ` Frank Rowand
2019-02-28 0:29 ` Brendan Higgins
2018-12-04 10:56 ` Frank Rowand
2018-11-28 19:36 ` [RFC v3 18/19] of: unittest: split out a couple of test cases from unittest Brendan Higgins
2018-12-04 10:58 ` Frank Rowand
2018-12-05 23:54 ` Brendan Higgins
2019-02-14 23:57 ` Frank Rowand
2019-02-15 0:56 ` Brendan Higgins
2019-02-15 2:05 ` Frank Rowand
2019-02-15 10:56 ` Brendan Higgins
2019-02-18 22:25 ` Frank Rowand
2019-02-20 20:44 ` Frank Rowand
2019-02-20 20:47 ` Frank Rowand
2019-02-28 3:52 ` Brendan Higgins
2019-03-22 0:22 ` Frank Rowand
2019-03-22 1:30 ` Brendan Higgins
2019-03-22 1:47 ` Frank Rowand
2019-03-25 22:15 ` Brendan Higgins
2019-09-20 16:57 ` Rob Herring
2019-09-21 23:57 ` Frank Rowand
2019-03-22 1:34 ` Frank Rowand
2019-03-25 22:18 ` Brendan Higgins
2018-11-28 19:36 ` [RFC v3 19/19] of: unittest: split up some super large test cases Brendan Higgins
2018-11-28 19:36 ` [RFC v3 16/19] arch: um: make UML unflatten device tree when testing Brendan Higgins
2018-11-28 21:16 ` Rob Herring
[not found] ` <CAL_JsqK5cG=QzMBFSZ31_-3ujnxqxv=jj3XYajbRLT7yWYZbfw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-04 0:00 ` Brendan Higgins
2018-11-30 3:46 ` Luis Chamberlain
2018-12-04 0:02 ` Brendan Higgins
2018-12-04 10:52 ` [RFC v3 00/19] kunit: introduce KUnit, the Linux kernel unit testing framework Frank Rowand
2018-12-04 11:40 ` Frank Rowand
2018-12-04 13:49 ` Rob Herring
2018-12-05 23:10 ` Brendan Higgins
2019-03-22 0:27 ` Frank Rowand
2019-03-25 22:04 ` Brendan Higgins
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAFd5g47pWbPso4LG93ffRUZjLhxnqws5VfYc5SfFf8FbuYCWvA@mail.gmail.com \
--to=brendanhiggins@google.com \
--cc=Tim.Bird@sony.com \
--cc=brakmo@fb.com \
--cc=dan.j.williams@intel.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=frowand.list@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=jdike@addtoit.com \
--cc=joe@perches.com \
--cc=joel@jms.id.au \
--cc=julia.lawall@lip6.fr \
--cc=keescook@google.com \
--cc=khilman@baylibre.com \
--cc=kieran.bingham@ideasonboard.com \
--cc=knut.omang@oracle.com \
--cc=kunit-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
--cc=linux-um@lists.infradead.org \
--cc=mcgrof@kernel.org \
--cc=mpe@ellerman.id.au \
--cc=pmladek@suse.com \
--cc=richard@nod.at \
--cc=robh@kernel.org \
--cc=rostedt@goodmis.org \
--cc=shuah@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).