linux-kernel - Re: [PATCH v10 0/5] Kernel parameter parser cleanup/enhancement

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Date:   Tue, 19 Jun 2018 16:36:47 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Michal Suchanek <msuchanek@...e.de>
Cc:     Jonathan Corbet <corbet@....net>, Arnd Bergmann <arnd@...db.de>,
        Frederic Weisbecker <frederic@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Aaron Wu <Aaron.Wu@...log.com>,
        Tony Luck <tony.luck@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Steven Rostedt," <rostedt@...dmis.org>,
        Laura Abbott <lauraa@...eaurora.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Jeffrey Hugo <jhugo@...eaurora.org>,
        Baoquan He <bhe@...hat.com>,
        Ilya Matveychikov <matvejchikov@...il.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 0/5] Kernel parameter parser cleanup/enhancement

On Tue,  5 Jun 2018 18:43:07 +0200 Michal Suchanek <msuchanek@...e.de> wrote:

> due to work on the fadump_extra_args I looked at the kernel parameter parser
> and found its grammar rather curious.
> 
> It supports double quotes but not any other quoting characters so double quotes
> cannot be quoted. What's more, the quotes can be anywhere in the parameter
> name or value and are interpteted but are removed only from start and end of
> the parameter value.
> 
> These are the patches not specific to fadump which somewhat straighten the
> qouting grammar to make it on par with common shell interpreters.
> 
> Specifically double and single quotes can be used for quoting as well as
> backslashes with the usual shell semantic. All quoting characters are removed
> while the parameters are parsed.

Well.  It's nice.  I guess.  Is there any demand for these
capabilities?  I don't recall ever having seen a complaint - kernel
parameters tend to be pretty simple things.


Also, the break_arg_end() and squash_char() macros make me want to cry.
A macro which changes control flow hidden inside another macro!  Are
they reeeealy necessary?  Can't be done with some C helpers?  Maybe put
inquote, backslash, args, i into a new struct parser_state and pass a
pointer to that around the place?  At the very least, those macros
should be apologetically documented :(