From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: loongarch@lists.linux.dev, linux-doc@vger.kernel.org,
dri-devel@lists.freedesktop.org,
"Brendan Higgins" <brendan.higgins@linux.dev>,
linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org,
"David Airlie" <airlied@gmail.com>,
"Arthur Grillo" <arthurgrillo@riseup.net>,
"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
"Daniel Diaz" <daniel.diaz@linaro.org>,
linux-sh@vger.kernel.org,
"Naresh Kamboju" <naresh.kamboju@linaro.org>,
"Maíra Canal" <mcanal@igalia.com>,
"Dan Carpenter" <dan.carpenter@linaro.org>,
netdev@lists.linux.dev, "Kees Cook" <keescook@chromium.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"David Gow" <davidgow@google.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
linux-arm-kernel@lists.infradead.org, kunit-dev@googlegroups.com,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/14] Add support for suppressing warning backtraces
Date: Thu, 14 Mar 2024 14:36:52 +0100 [thread overview]
Message-ID: <CAMuHMdUkvagJVEfnhq=Nx2jnmdS0Ax+zy1CvyN0k7k1EwUpu+g@mail.gmail.com> (raw)
In-Reply-To: <20240312170309.2546362-1-linux@roeck-us.net>
Hi Günter,
On Tue, Mar 12, 2024 at 6:03 PM Guenter Roeck <linux@roeck-us.net> wrote:
> Some unit tests intentionally trigger warning backtraces by passing bad
> parameters to kernel API functions. Such unit tests typically check the
> return value from such calls, not the existence of the warning backtrace.
>
> Such intentionally generated warning backtraces are neither desirable
> nor useful for a number of reasons.
> - They can result in overlooked real problems.
> - A warning that suddenly starts to show up in unit tests needs to be
> investigated and has to be marked to be ignored, for example by
> adjusting filter scripts. Such filters are ad-hoc because there is
> no real standard format for warnings. On top of that, such filter
> scripts would require constant maintenance.
>
> One option to address problem would be to add messages such as "expected
> warning backtraces start / end here" to the kernel log. However, that
> would again require filter scripts, it might result in missing real
> problematic warning backtraces triggered while the test is running, and
> the irrelevant backtrace(s) would still clog the kernel log.
>
> Solve the problem by providing a means to identify and suppress specific
> warning backtraces while executing test code. Support suppressing multiple
> backtraces while at the same time limiting changes to generic code to the
> absolute minimum. Architecture specific changes are kept at minimum by
> retaining function names only if both CONFIG_DEBUG_BUGVERBOSE and
> CONFIG_KUNIT are enabled.
>
> The first patch of the series introduces the necessary infrastructure.
> The second patch introduces support for counting suppressed backtraces.
> This capability is used in patch three to implement unit tests.
> Patch four documents the new API.
> The next two patches add support for suppressing backtraces in drm_rect
> and dev_addr_lists unit tests. These patches are intended to serve as
> examples for the use of the functionality introduced with this series.
> The remaining patches implement the necessary changes for all
> architectures with GENERIC_BUG support.
Thanks for your series!
I gave it a try on m68k, just running backtrace-suppression-test,
and that seems to work fine.
> Design note:
> Function pointers are only added to the __bug_table section if both
> CONFIG_KUNIT and CONFIG_DEBUG_BUGVERBOSE are enabled to avoid image
> size increases if CONFIG_KUNIT=n. There would be some benefits to
> adding those pointers all the time (reduced complexity, ability to
> display function names in BUG/WARNING messages). That change, if
> desired, can be made later.
Unfortunately this also increases kernel size in the CONFIG_KUNIT=m
case (ca. 80 KiB for atari_defconfig), making it less attractive to have
kunit and all tests enabled as modules in my standard kernel.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2024-03-14 13:37 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-12 17:02 [PATCH 00/14] Add support for suppressing warning backtraces Guenter Roeck
2024-03-12 17:02 ` [PATCH 01/14] bug/kunit: Core " Guenter Roeck
2024-03-12 22:00 ` Kees Cook
2024-03-12 17:02 ` [PATCH 02/14] kunit: bug: Count suppressed " Guenter Roeck
2024-03-12 22:02 ` Kees Cook
2024-03-12 17:02 ` [PATCH 03/14] kunit: Add test cases for backtrace warning suppression Guenter Roeck
2024-03-12 22:02 ` Kees Cook
2024-03-12 17:02 ` [PATCH 04/14] kunit: Add documentation for warning backtrace suppression API Guenter Roeck
2024-03-12 22:03 ` Kees Cook
2024-03-12 17:03 ` [PATCH 05/14] drm: Suppress intentional warning backtraces in scaling unit tests Guenter Roeck
2024-03-12 17:03 ` [PATCH 06/14] net: kunit: Suppress lock warning noise at end of dev_addr_lists tests Guenter Roeck
2024-03-12 17:03 ` [PATCH 07/14] x86: Add support for suppressing warning backtraces Guenter Roeck
2024-03-12 17:03 ` [PATCH 08/14] arm64: " Guenter Roeck
2024-03-12 17:03 ` [PATCH 09/14] loongarch: " Guenter Roeck
2024-03-12 17:03 ` [PATCH 10/14] parisc: " Guenter Roeck
2024-03-15 11:45 ` Helge Deller
2024-03-12 17:03 ` [PATCH 11/14] s390: " Guenter Roeck
2024-03-14 7:57 ` Geert Uytterhoeven
2024-03-14 13:54 ` Guenter Roeck
2024-03-12 17:03 ` [PATCH 12/14] sh: " Guenter Roeck
2024-03-12 17:03 ` [PATCH 13/14] riscv: " Guenter Roeck
2024-03-12 17:03 ` [PATCH 14/14] powerpc: " Guenter Roeck
2024-03-13 7:39 ` [PATCH 00/14] " Dan Carpenter
2024-03-14 7:19 ` Naresh Kamboju
2024-03-14 13:36 ` Geert Uytterhoeven [this message]
2024-03-14 14:37 ` Guenter Roeck
2024-03-14 15:02 ` Maxime Ripard
2024-03-14 15:29 ` Guenter Roeck
2024-03-16 16:16 ` Guenter Roeck
2024-03-18 3:24 ` Michael Ellerman
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