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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"Linux Crypto Mailing List" <linux-crypto@vger.kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Sultan Alsawaf" <sultan@kerneltoast.com>,
	"Jonathan Neuschäfer" <j.neuschaefer@gmx.net>,
	"Dominik Brodowski" <linux@dominikbrodowski.net>
Subject: Re: [PATCH v6] random: defer fast pool mixing to worker
Date: Mon, 14 Feb 2022 10:16:53 +0100	[thread overview]
Message-ID: <YgoeBYJ5nwc8BTG3@linutronix.de> (raw)
In-Reply-To: <CAHmME9rsOWuprpYqo9G9eUboQwUxRgWqYRYgyHG7cNOG16c5EA@mail.gmail.com>

On 2022-02-13 18:37:33 [+0100], Jason A. Donenfeld wrote:
> I started looking at this and came up with this draft with questions:
> https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/commit/?h=jd/no-irq-trylocks

to
| - Does anything anywhere call get_random_xx() before the worker has a
|   chance to run?

Once you queue a work item I don't think that the scheduler needs to put
it on the CPU right away. It may have already have other tasks waiting
including some with a RT priority.
Also, the lock is irqsave() so they can be users in an interrupt
handler. I remember the original reason why I made it irqsave is because
something did kmalloc() and SLUB somehow asked for random bits.

> Some research remains...
> 
> Jason

Sebastian

  reply	other threads:[~2022-02-14  9:16 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-11 13:08 [PATCH v5] random: defer fast pool mixing to worker Jason A. Donenfeld
2022-02-11 15:00 ` Sebastian Andrzej Siewior
2022-02-11 16:25   ` [PATCH v6] " Jason A. Donenfeld
2022-02-11 16:44     ` Sebastian Andrzej Siewior
2022-02-11 16:50       ` Jason A. Donenfeld
2022-02-11 16:58         ` Sebastian Andrzej Siewior
2022-02-11 17:00           ` Jason A. Donenfeld
2022-02-11 17:15             ` Sebastian Andrzej Siewior
2022-02-11 17:17               ` Jason A. Donenfeld
2022-02-11 17:26                 ` Sebastian Andrzej Siewior
2022-02-13 21:04                   ` Jason A. Donenfeld
2022-02-14 10:19                     ` Jason A. Donenfeld
2022-02-13 17:37           ` Jason A. Donenfeld
2022-02-14  9:16             ` Sebastian Andrzej Siewior [this message]
2022-02-14 10:17               ` Jason A. Donenfeld
2022-02-14 11:16                 ` Sebastian Andrzej Siewior
2022-02-14 14:47                   ` Jason A. Donenfeld
2022-02-11 17:07         ` [PATCH v7] " Jason A. Donenfeld
2022-02-11 17:20           ` Sultan Alsawaf
2022-02-11 17:24           ` Sebastian Andrzej Siewior

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