On Sat, Mar 10, 2018 at 11:09:59AM +0100, Christoph Hellwig wrote:

quoted

+static void hpsa_setup_reply_map(struct ctlr_info *h)
+{
+	const struct cpumask *mask;
+	unsigned int queue, cpu;
+
+	for (queue = 0; queue < h->msix_vectors; queue++) {
+		mask = pci_irq_get_affinity(h->pdev, queue);
+		if (!mask)
+			goto fallback;
+
+		for_each_cpu(cpu, mask)
+			h->reply_map[cpu] = queue;
+	}
+	return;
+
+fallback:
+	for_each_possible_cpu(cpu)
+		h->reply_map[cpu] = 0;
+}

quoted

+	h->reply_map = kzalloc(sizeof(*h->reply_map) * nr_cpu_ids, GFP_KERNEL);
+	if (!h->reply_map) {
+		kfree(h);
+		return NULL;
+	}
+	return h;

I really dislike this being open coded in drivers.  It really should
be helper chared with the blk-mq map building that drivers just use.

For now just have a low-level blk_pci_map_queues that
blk_mq_pci_map_queues, hpsa and megaraid can share.  In the long run
it might make sense to change the blk-mq callout to that low-level
prototype as well.

The way for selecting reply queue is needed for non scsi_mq too.

Thanks,
Ming