linux-kernel - Re: [PATCH RFC 1/2] coding-style.rst: document BUG() and WARN() rules ("do not crash the kernel")

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Message-ID: <87tu5vflld.fsf@intel.com>
Date:   Mon, 29 Aug 2022 12:25:02 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Dave Young <dyoung@...hat.com>
Cc:     David Hildenbrand <david@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-doc@...r.kernel.org, kexec@...ts.infradead.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        David Laight <David.Laight@...lab.com>,
        Jonathan Corbet <corbet@....net>,
        Andy Whitcroft <apw@...onical.com>,
        Joe Perches <joe@...ches.com>,
        Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Stephen Johnston <sjohnsto@...hat.com>,
        Prarit Bhargava <prarit@...hat.com>
Subject: Re: [PATCH RFC 1/2] coding-style.rst: document BUG() and WARN()
 rules ("do not crash the kernel")

On Sun, 28 Aug 2022, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> So WARN_ON_ONCE() is the thing to aim for. BUG_ON() is the thing for
> "oops, I really don't know what to do, and I physically *cannot*
> continue" (and that is *not* "I'm too lazy to do error handling").

Any insight for the tradeoff between WARN_ON_ONCE() and WARN_ON(),
i.e. wasting the static once variable per use site vs. littering the
dmesg on every hit? I see there have been some improvements with the
__WARN_FLAGS() stuff, but is the data use really neglible?

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center