linux-kernel - Re: [PATCH RESEND 1/3] printk: convert byte-buffer to variable-length record buffer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+55aFzVs0GLpNVUBHtLRuc8uQc=WKd8ajeVWsffbNvxSQvB4Q@mail.gmail.com>
Date:	Tue, 8 May 2012 21:27:12 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	Kay Sievers <kay@...y.org>, Greg Kroah-Hartmann <greg@...ah.com>,
	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND 1/3] printk: convert byte-buffer to variable-length
 record buffer

On Tue, May 8, 2012 at 9:11 PM, Sasha Levin <levinsasha928@...il.com> wrote:
>
> Is there a reason to keep KERN_CONT under this set of rules at all?

Yes, a very subtle and rare one.

If you want to print out a string that starts with "<%d>", you *have*
to use a prefix, in order to not make printk think that the "<*>" is
the prefix itself.

And if you don't want to start a new line, you need to use KERN_CONT.

So there is *one* case, and one case only, where KERN_CONT is useful,
and it's when the string you are printing out could otherwise be
mistaken for a prefix itself (the "<%d>" thing isn't the only such
string, of course - it could be a "%s" where the string has those
characters in it.

So think of KERN_CONT as a "quoting safety" thing. And in 99% of all
cases it is obviously not actually needed. So in general, KERN_CONT is
useless and should not be used, but that doesn't mean that it can be
removed as a _concept_.

               Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/