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Date:   Wed, 12 Jul 2023 15:00:17 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        linux-nvme@lists.infradead.org,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        linux-scsi@vger.kernel.org, linux-block@vger.kernel.org,
        Wen Xiong <wenxiong@linux.ibm.com>,
        Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH 1/8] blk-mq: add blk_mq_max_nr_hw_queues()
Message-ID: <20230712130017.GA12417@lst.de>
References: <20230712125455.1986455-1-ming.lei@redhat.com> <20230712125455.1986455-2-ming.lei@redhat.com>
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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.