Re: [PATCH 1/8] blk-mq: add blk_mq_max_nr_hw_queues()

[Christoph Hellwig <hch@lst.de>]

On Wed, Jul 12, 2023 at 08:54:48PM +0800, Ming Lei wrote:
> +/* Max nr_hw_queues for each hw queue type */
> +unsigned int blk_mq_max_nr_hw_queues(void)
> +{
> +	if (is_kdump_kernel())
> +		return 1;
> +	return nr_cpu_ids;

Again, these is_kdump_kernel hacks don't make any sense.   The amount
of maximum available CPU needs to come through a proper API, and we
need to use it, not add hacks like this.

The only thing that makes sense here is to find the last CPU
in cpu_possible_mask, and for kdump kernels to ensure that number
is 1 or whatever low value they want.