linux-kernel - Re: [PATCH v4 6/9] vsprintf: Factor out %pV handler as va

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Message-ID: <20180406131242.mnxutlobi7r6qi6u@pathway.suse.cz>
Date:   Fri, 6 Apr 2018 15:12:42 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 6/9] vsprintf: Factor out %pV handler as va_format()

On Wed 2018-04-04 07:26:07, Joe Perches wrote:
> On Wed, 2018-04-04 at 10:58 +0200, Petr Mladek wrote:
> > Move the code from the long pointer() function. We are going to add a check
> > for the access to the address that will make it even more complicated.
> > 
> > This patch does not change the existing behavior.
> 
> But it might increase stack consumption.
> 
> As the %pV is recursive, this is may not be a good thing.

It seems to be safe to pass just a pointer to struct printf_spec.
In fact, it would make sense to use this also in string() and
__string() calls. Copying 64 bytes many times look useless.

Do you think that other optimizations would be necessary?
For example, marking the function as inline?

Best Regards,
Petr