linux-kernel - Re: [PATCH v2] random: do crng pre-init loading in worker rather than irq

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Date:   Mon, 28 Feb 2022 16:34:29 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Eric Biggers <ebiggers@...nel.org>,
        Theodore Ts'o <tytso@....edu>,
        Dominik Brodowski <linux@...inikbrodowski.net>
Subject: Re: [PATCH v2] random: do crng pre-init loading in worker rather
 than irq

On 2022-02-28 16:10:38 [+0100], Jason A. Donenfeld wrote:
> Hi Sebastian,
Hi Jason,

> Ahh, I understand, okay. Yes, I'll change that first paragraph to
> incorporate your wording, as:
> 
> """
> Taking spinlocks from IRQ context is generally problematic for
> PREEMPT_RT. That is, in part, why we take trylocks instead. However, a
> spin_try_lock() is also problematic since another spin_lock() invocation
> can potentially PI-boost the wrong task, as the spin_try_lock() is
> invoked from an IRQ-context, so the task on CPU (random task or idle) is
> not the actual owner.
> """

I didn't expect it that verbose but yes, full ACK from side.
Thank you.

> Jason

Sebastian