Re: [PATCH v3] random: remove batched entropy locking

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

On 2022-02-04 16:51:42 [+0100], Jason A. Donenfeld wrote:
> index 455615ac169a..3e54b90a3ff8 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1759,41 +1762,54 @@ u64 get_random_u64(void)
>  	unsigned long flags;
>  	struct batched_entropy *batch;
>  	static void *previous;
> +	int next_gen;
>  
>  	warn_unseeded_randomness(&previous);
>  
> -	batch = raw_cpu_ptr(&batched_entropy_u64);
> -	spin_lock_irqsave(&batch->batch_lock, flags);
> -	if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
> +	batch = this_cpu_ptr(&batched_entropy_u64);
> +	local_lock_irqsave(&batch->lock, flags);

Does this compile and work? From the looks of it, this should be:

	local_lock_irqsave(&batched_entropy_u64.lock, flags);
	batch = this_cpu_ptr(&batched_entropy_u64);

and we could do s/this_cpu_ptr/raw_cpu_ptr/

Sebastian