From: Kees Cook <kees@kernel.org>
To: Alessandro Carminati <acarmina@redhat.com>
Cc: linux-kselftest@vger.kernel.org,
Dan Carpenter <dan.carpenter@linaro.org>,
Daniel Diaz <daniel.diaz@linaro.org>,
David Gow <davidgow@google.com>,
Arthur Grillo <arthurgrillo@riseup.net>,
Brendan Higgins <brendan.higgins@linux.dev>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
Andrew Morton <akpm@linux-foundation.org>,
Maxime Ripard <mripard@kernel.org>,
Ville Syrjala <ville.syrjala@linux.intel.com>,
Daniel Vetter <daniel@ffwll.ch>,
Guenter Roeck <linux@roeck-us.net>,
Alessandro Carminati <alessandro.carminati@gmail.com>,
Jani Nikula <jani.nikula@intel.com>,
Jeff Johnson <jeff.johnson@oss.qualcomm.com>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Linux Kernel Functional Testing <lkft@linaro.org>,
dri-devel@lists.freedesktop.org, kunit-dev@googlegroups.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/5] bug/kunit: Suppressing warning backtraces reduced impact on WARN*() sites
Date: Wed, 28 May 2025 15:52:36 -0700 [thread overview]
Message-ID: <202505281549.9B51A7D2@keescook> (raw)
In-Reply-To: <20250526132755.166150-3-acarmina@redhat.com>
On Mon, May 26, 2025 at 01:27:52PM +0000, Alessandro Carminati wrote:
> KUnit support is not consistently present across distributions, some
> include it in their stock kernels, while others do not.
> While both KUNIT and KUNIT_SUPPRESS_BACKTRACE can be considered debug
> features, the fact that some distros ship with KUnit enabled means it's
> important to minimize the runtime impact of this patch.
> To that end, this patch introduces a counter for the number of
> suppressed symbols and skips execution of __kunit_is_suppressed_warning()
> entirely when no symbols are currently being suppressed.
If KUnit already serialized? I should have asked this before: you're
reading and writing a global list -- I think some kind of RCU may
be needed for the list? One thread may be removing a function from the
list while another thread is executing a WARN-induced walk of the
list...
This global may have the same problem. Why not use a static branch, or
is that just overkill?
-Kees
--
Kees Cook
next prev parent reply other threads:[~2025-05-28 22:52 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-26 13:27 [PATCH v5 0/5] kunit: Add support for suppressing warning backtraces Alessandro Carminati
2025-05-26 13:27 ` [PATCH v5 1/5] bug/kunit: Core " Alessandro Carminati
2025-05-28 22:47 ` Kees Cook
2025-05-29 9:02 ` Peter Zijlstra
2025-05-29 17:46 ` Kees Cook
2025-05-30 9:25 ` Peter Zijlstra
2025-05-29 9:01 ` Peter Zijlstra
2025-05-29 10:36 ` Alessandro Carminati
2025-05-30 14:01 ` Peter Zijlstra
2025-05-30 17:48 ` Kees Cook
2025-05-31 10:23 ` Peter Zijlstra
2025-05-31 13:51 ` Kees Cook
2025-06-02 7:57 ` Peter Zijlstra
2025-06-02 10:38 ` Maxime Ripard
2025-06-03 11:40 ` Simona Vetter
2025-06-02 11:13 ` Maxime Ripard
2025-06-03 12:26 ` Peter Zijlstra
2025-06-04 3:30 ` Daniel Latypov
2025-06-06 8:05 ` Maxime Ripard
2025-05-31 10:25 ` Peter Zijlstra
2025-05-31 7:46 ` Peter Zijlstra
2025-05-31 7:52 ` Alessandro Carminati
2025-05-30 9:26 ` Peter Zijlstra
2025-05-26 13:27 ` [PATCH v5 2/5] bug/kunit: Suppressing warning backtraces reduced impact on WARN*() sites Alessandro Carminati
2025-05-28 22:52 ` Kees Cook [this message]
2025-05-26 13:27 ` [PATCH v5 3/5] Add unit tests to verify that warning backtrace suppression works Alessandro Carminati
2025-05-26 13:27 ` [PATCH v5 4/5] drm: Suppress intentional warning backtraces in scaling unit tests Alessandro Carminati
2025-05-26 13:27 ` [PATCH v5 5/5] kunit: Add documentation for warning backtrace suppression API Alessandro Carminati
2025-06-02 7:24 ` [PATCH v5 0/5] kunit: Add support for suppressing warning backtraces Dan Carpenter
2025-06-02 10:47 ` Maxime Ripard
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