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Date: Wed, 25 Sep 2013 15:35:30 +0200 From: Hannes Frederic Sowa <hannes@...essinduktion.org> To: Eric Dumazet <eric.dumazet@...il.com> 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, Sep 25, 2013 at 05:06:50AM -0700, Eric Dumazet wrote: > 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 ? We increase the entropy_count and can initialize the random pool from handle_irq_event. We can document that it should not get called from irq context and maybe add a WARN_ON(irqs_disabled())? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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