linux-kernel - Re: [PATCH] random: Initialize vsprintf's pointer hash once the random core is ready.

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Message-ID: <YuO0p8lMhVmQj/K2@linutronix.de>
Date:   Fri, 29 Jul 2022 12:21:27 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        John Ogness <john.ogness@...utronix.de>,
        Mike Galbraith <efault@....de>, Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] random: Initialize vsprintf's pointer hash once the
 random core is ready.

On 2022-07-29 12:12:08 [+0200], Jason A. Donenfeld wrote:
> Hi Sebastian,
Hi Jason,

> Gumming up random.c with these sorts of things isn't alright. vsprintf
> isn't special in any regard here.
> 
> If you can't do this from ordinary context inside of vsprintf, just
> launch a workqueue to do it. This is already needed for changing
> vsprintf's static branch, so just move the get_random_bytes() call into
> there on RT (leaving it alone on non-RT, I guess).

So launching a worker to obtain the random data? That would mean that
the first %p print won't have nothing, right? I could do it as part of
an init-call but I don't know when the random pool is ready. And trying
it again every other second if the random core isn't ready looks kind of
wasteful.

> Jason

Sebastian