netdev - Re: [PATCH RFC] random: introduce get_random_bytes_busy_wait

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Message-ID: <1380110810.3165.140.camel@edumazet-glaptop>
Date:	Wed, 25 Sep 2013 05:06:50 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	Tom Herbert <therbert@...gle.com>, davem@...emloft.net,
	netdev@...r.kernel.org, jesse.brandeburg@...el.com, tytso@....edu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] random: introduce
 get_random_bytes_busy_wait_initialized

On Wed, 2013-09-25 at 11:00 +0200, Hannes Frederic Sowa wrote:

>  /*
> + * Busy loop until the nonblocking_pool is intialized and return
> + * random data in buf of size nbytes.
> + *
> + * This is used by the network stack to defer the extraction of
> + * entropy from the nonblocking_pool until the pool is initialized.
> + *
> + * We need to busy loop here, because we could be called from an
> + * atomic section.
> + */
> +void get_random_bytes_busy_wait_initialized(void *buf, int nbytes)
> +{
> +	while (!nonblocking_pool.initialized)
> +		cpu_relax();
> +	get_random_bytes(buf, nbytes);
> +}

No idea if this can work if called from IRQ context.

How is nonblocking_poll initialized if host has a single cpu ?



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