linux-kernel - Re: [PATCH] random: remove mostly unused async readiness notifier

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Message-ID: <YoTB2OlwQq4J4/2D@zx2c4.com>
Date:   Wed, 18 May 2022 11:52:24 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH] random: remove mostly unused async readiness notifier

Hi Petr,

On Wed, May 18, 2022 at 10:54:22AM +0200, Petr Mladek wrote:
> > +		spin_lock_irqsave(&filling, flags);
> 
> I thought more about this and there is a small risk of a deadlock
> when get_random_bytes() or queue_work() or NMI calls
> printk()/vsprintf() with %p here.
> 
> A simple solution would be to use trylock():
> 
> 		if (!spin_trylock_irqsave(&filling, flags))
> 			return -EDEADLK;
> 
> Could we do this change, please?
> 
> I do not mind if it will be done by re-spinning the original
> patch or another patch on top of it.

Interesting consideration. Sure, I'll do exactly that and send a v2.

Jason