On Tue, Nov 12, 2024 at 05:15:31PM +0100, Daniel Wagner wrote:
> On Tue, Nov 12, 2024 at 04:42:40PM +0100, Greg Kroah-Hartman wrote:
> > On Tue, Nov 12, 2024 at 04:33:09PM +0100, Daniel Wagner wrote:
> > > On Tue, Nov 12, 2024 at 02:58:43PM +0100, Greg Kroah-Hartman wrote:
> > > > > +void blk_mq_hctx_map_queues(struct blk_mq_queue_map *qmap,
> > > > > + struct device *dev, unsigned int offset)
> > > > > +
> > > > > +{
> > > > > + const struct cpumask *mask;
> > > > > + unsigned int queue, cpu;
> > > > > +
> > > > > + if (!dev->bus->irq_get_affinity)
> > > > > + goto fallback;
> > > >
> > > > I think this is better than hard-coding it, but are you sure that the
> > > > bus will always be bound to the device here so that you have a valid
> > > > bus-> pointer?
> > >
> > > No, I just assumed the bus pointer is always valid. If it is possible to
> > > have a device without a bus, than I'll better extend the condition to
> > >
> > > if (!dev->bus || !dev->bus->irq_get_affinity)
> > > goto fallback;
> >
> > I don't know if it's possible as I don't know what codepaths are calling
> > this, it was hard to unwind. But you should check "just to be safe" :)
>
> The main path to map_queues is via the probe functions. There are some
> more paths like when updating a tagset after the number of queues but
> that is all after the probe function.
>
> nvme_probe
> nvme_alloc_admin_tag_set
> blk_mq_alloc_tag_set
> blk_mq_update_queue_map
> set->ops->map_queues
> blk_mq_htcx_map_queues
> nvme_alloc_io_tag_set
> blk_mq_alloc_tag_set
> blk_mq_update_queue_map
> set->ops->map_queues
> blk_mq_htcx_map_queues
>
> virtscsi_probe, hisi_sas_v3_probe, ...
> scsi_add_host
> scsi_add_host_with_dma
> scsi_mq_setup_tags
> blk_mq_alloc_tag_set
> blk_mq_update_queue_map
> set->ops->map_queues
> blk_mq_htcx_map_queues
>
> virtblk_probe
> blk_mq_alloc_tag_set
> blk_mq_update_queue_map
> set->ops->map_queues
> blk_mq_htcx_map_queues
>
> Does this help?
Ok, that seems fine. Worst case, you crash and it's obvious that it
needs to be checked in the future :)
thanks,
greg k-h
