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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Jason@zx2c4.com, linux-kernel@vger.kernel.org, tytso@mit.edu,
	tglx@linutronix.de, peterz@infradead.org
Subject: Re: [PATCH 5/5] random: Defer processing of randomness on PREEMPT_RT.
Date: Fri, 17 Dec 2021 13:23:38 +1100	[thread overview]
Message-ID: <20211217022338.GA19411@gondor.apana.org.au> (raw)
In-Reply-To: <20211207201037.h46573oa5nfj33xq@linutronix.de>

Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
>
> Even the IOCTL path must spin with disabled interrupts to avoid dead
> locks. Therefore it makes no sense if attempt acquire the lock from
> process or IRQ context. Something like
>        while (!raw_spin_trylock_irqsave())
>                cpu_relax()

What about the TCP socket locking model?

IOW, the user-space slow path will add itself to a backlog queue
during contention, and the interrupt fast path will schedule work
to process any user-space backlog on exit.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  parent reply	other threads:[~2021-12-17  2:23 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-07 12:17 [PATCH 0/5] random: Add PREEMPT_RT support Sebastian Andrzej Siewior
2021-12-07 12:17 ` [PATCH 1/5] random: Remove unused irq_flags argument from add_interrupt_randomness() Sebastian Andrzej Siewior
2021-12-07 12:44   ` Wei Liu
2021-12-07 17:35   ` Jason A. Donenfeld
2021-12-07 12:17 ` [PATCH 2/5] irq: Remove unsued flags argument from __handle_irq_event_percpu() Sebastian Andrzej Siewior
2021-12-07 17:41   ` Jason A. Donenfeld
2021-12-11 22:39     ` Thomas Gleixner
2021-12-12 21:13       ` Jason A. Donenfeld
2021-12-07 12:17 ` [PATCH 3/5] random: Split add_interrupt_randomness() Sebastian Andrzej Siewior
2021-12-07 12:17 ` [PATCH 4/5] random: Move the fast_pool reset into the caller Sebastian Andrzej Siewior
2021-12-07 12:17 ` [PATCH 5/5] random: Defer processing of randomness on PREEMPT_RT Sebastian Andrzej Siewior
2021-12-07 18:14   ` Jason A. Donenfeld
2021-12-07 20:10     ` Sebastian Andrzej Siewior
2021-12-13 15:16       ` Sebastian Andrzej Siewior
2021-12-17  2:23       ` Herbert Xu [this message]
2021-12-17  9:00         ` Sebastian Andrzej Siewior
2021-12-18  3:24           ` Herbert Xu
2021-12-19  9:48             ` Sebastian Andrzej Siewior
2021-12-20  2:56               ` Herbert Xu
2021-12-20 14:38       ` Jason A. Donenfeld
2022-01-12 17:49         ` Sebastian Andrzej Siewior
2022-01-30 22:55           ` Jason A. Donenfeld
2022-01-31 16:33             ` Sebastian Andrzej Siewior
2022-02-04 15:31               ` [PATCH RFC v1] random: do not take spinlocks in irq handler Jason A. Donenfeld
2022-02-04 15:58                 ` Jason A. Donenfeld
2022-02-04 20:53                   ` Sebastian Andrzej Siewior
2022-02-04 20:47                 ` Sebastian Andrzej Siewior
2022-02-04 22:08                   ` Jason A. Donenfeld
2022-02-04 23:09                     ` [PATCH v2] random: defer fast pool mixing to worker Jason A. Donenfeld
2022-02-05  4:02                   ` [PATCH RFC v1] random: do not take spinlocks in irq handler Sultan Alsawaf
2022-02-05 12:50                     ` Jason A. Donenfeld

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