Re: [PATCH v6] random: clear fast pool, crng, and batches in cpuhp bring up

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2022-02-17 19:04:09 [+0100], Jason A. Donenfeld wrote:
> For the irq randomness fast pool, rather than having to use expensive
> atomics, which were visibly the most expensive thing in the entire irq
> handler, simply take care of the extreme edge case of resetting count to
> zero in the cpuhp online handler, just after workqueues have been
> reenabled. This simplifies the code a bit and lets us use vanilla
> variables rather than atomics, and performance should be improved.
> 
> As well, very early on when the CPU comes up, while interrupts are still
> disabled, we clear out the per-cpu crng and its batches, so that it
> always starts with fresh randomness.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Sultan Alsawaf <sultan@kerneltoast.com>
> Cc: Dominik Brodowski <linux@dominikbrodowski.net>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> v6 improves the comments around each of the cpuhp functions, as
> requested.

Perfect thank you.
Did you miss my question regarding cross-CPU init in
random_prepare_cpu()?

Sebastian