Re: [PATCH V4 3/4] Introduce XEN scsiback module

[Christoph Hellwig <hch@infradead.org>]

> +#include <scsi/scsi_dbg.h>
> +#include <scsi/scsi_eh.h>
> +#include <scsi/scsi_tcq.h>

What do you need these for?  Normally target drivers shouldn't need
these.

> +struct vscsibk_emulate {
> +	void (*pre_function)(struct vscsibk_pend *, void *);
> +	void (*post_function)(struct vscsibk_pend *, void *);
> +};

This doesn't seem to be used.

> +#define scsiback_get(_b) (atomic_inc(&(_b)->nr_unreplied_reqs))
> +#define scsiback_put(_b)				\
> +	do {						\
> +		if (atomic_dec_and_test(&(_b)->nr_unreplied_reqs))	\
> +			wake_up(&(_b)->waiting_to_free);\
> +	} while (0)

Normal Linux style would be to make these inline functions.

> +static void scsiback_notify_work(struct vscsibk_info *info)
> +{
> +	info->waiting_reqs = 1;
> +	wake_up(&info->wq);
> +}
> +
> +static irqreturn_t scsiback_intr(int irq, void *dev_id)
> +{
> +	scsiback_notify_work((struct vscsibk_info *)dev_id);
> +	return IRQ_HANDLED;
> +}

Seems like this driver should get the same threaded irq treatment as
the initiator side?

> +static void scsiback_disconnect(struct vscsibk_info *info)
> +{
> +	if (info->kthread) {
> +		kthread_stop(info->kthread);
> +		info->kthread = NULL;
> +		wake_up(&info->shutdown_wq);
> +	}
> +
> +	wait_event(info->waiting_to_free,
> +		atomic_read(&info->nr_unreplied_reqs) == 0);
> +
> +	if (info->irq) {
> +		unbind_from_irqhandler(info->irq, info);
> +		info->irq = 0;
> +	}
> +
> +	if (info->ring.sring) {
> +		xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
> +		info->ring.sring = NULL;
> +	}
> +}

Also the same treatment for goto based init failure unwinding.