Messages in this thread | | | Date | Mon, 28 Feb 2022 15:02:59 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH v2] random: do crng pre-init loading in worker rather than irq |
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On 2022-02-24 16:29:37 [+0100], Jason A. Donenfeld wrote: > Taking spinlocks from IRQ context is problematic for PREEMPT_RT. That > is, in part, why we take trylocks instead. But apparently this still > trips up various lock dependency analyzers. That seems like a bug in the > analyzers that should be fixed, rather than having to change things > here.
Could you please post a lockdep report so I can take a look?
> But maybe there's another reason to change things up: by deferring the > crng pre-init loading to the worker, we can use the cryptographic hash > function rather than xor, which is perhaps a meaningful difference when > considering this data has only been through the relatively weak > fast_mix() function. > > The biggest downside of this approach is that the pre-init loading is > now deferred until later, which means things that need random numbers > after interrupts are enabled, but before workqueues are running -- or > before this particular worker manages to run -- are going to get into > trouble. Hopefully in the real world, this window is rather small, > especially since this code won't run until 64 interrupts had occurred. > > Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Eric Biggers <ebiggers@kernel.org> > Cc: Theodore Ts'o <tytso@mit.edu> > Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Other than that:
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Sebastian
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