static int generic_request()

in sunvdc.c [574:712]

• 105 lines of code
• 21 McCabe index (conditional complexity)

static int generic_request(struct vdc_port *port, u8 op, void *buf, int len)
{
	struct vio_dring_state *dr;
	struct vio_completion comp;
	struct vio_disk_desc *desc;
	unsigned int map_perm;
	unsigned long flags;
	int op_len, err;
	void *req_buf;

	if (!(((u64)1 << (u64)op) & port->operations))
		return -EOPNOTSUPP;

	switch (op) {
	case VD_OP_BREAD:
	case VD_OP_BWRITE:
	default:
		return -EINVAL;

	case VD_OP_FLUSH:
		op_len = 0;
		map_perm = 0;
		break;

	case VD_OP_GET_WCE:
		op_len = sizeof(u32);
		map_perm = LDC_MAP_W;
		break;

	case VD_OP_SET_WCE:
		op_len = sizeof(u32);
		map_perm = LDC_MAP_R;
		break;

	case VD_OP_GET_VTOC:
		op_len = sizeof(struct vio_disk_vtoc);
		map_perm = LDC_MAP_W;
		break;

	case VD_OP_SET_VTOC:
		op_len = sizeof(struct vio_disk_vtoc);
		map_perm = LDC_MAP_R;
		break;

	case VD_OP_GET_DISKGEOM:
		op_len = sizeof(struct vio_disk_geom);
		map_perm = LDC_MAP_W;
		break;

	case VD_OP_SET_DISKGEOM:
		op_len = sizeof(struct vio_disk_geom);
		map_perm = LDC_MAP_R;
		break;

	case VD_OP_SCSICMD:
		op_len = 16;
		map_perm = LDC_MAP_RW;
		break;

	case VD_OP_GET_DEVID:
		op_len = sizeof(struct vio_disk_devid);
		map_perm = LDC_MAP_W;
		break;

	case VD_OP_GET_EFI:
	case VD_OP_SET_EFI:
		return -EOPNOTSUPP;
	}

	map_perm |= LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;

	op_len = (op_len + 7) & ~7;
	req_buf = kzalloc(op_len, GFP_KERNEL);
	if (!req_buf)
		return -ENOMEM;

	if (len > op_len)
		len = op_len;

	if (map_perm & LDC_MAP_R)
		memcpy(req_buf, buf, len);

	spin_lock_irqsave(&port->vio.lock, flags);

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];

	/* XXX If we want to use this code generically we have to
	 * XXX handle TX ring exhaustion etc.
	 */
	desc = vio_dring_cur(dr);

	err = ldc_map_single(port->vio.lp, req_buf, op_len,
			     desc->cookies, port->ring_cookies,
			     map_perm);
	if (err < 0) {
		spin_unlock_irqrestore(&port->vio.lock, flags);
		kfree(req_buf);
		return err;
	}

	init_completion(&comp.com);
	comp.waiting_for = WAITING_FOR_GEN_CMD;
	port->vio.cmp = &comp;

	desc->hdr.ack = VIO_ACK_ENABLE;
	desc->req_id = port->req_id;
	desc->operation = op;
	desc->slice = 0;
	desc->status = ~0;
	desc->offset = 0;
	desc->size = op_len;
	desc->ncookies = err;

	/* This has to be a non-SMP write barrier because we are writing
	 * to memory which is shared with the peer LDOM.
	 */
	wmb();
	desc->hdr.state = VIO_DESC_READY;

	err = __vdc_tx_trigger(port);
	if (err >= 0) {
		port->req_id++;
		dr->prod = vio_dring_next(dr, dr->prod);
		spin_unlock_irqrestore(&port->vio.lock, flags);

		wait_for_completion(&comp.com);
		err = comp.err;
	} else {
		port->vio.cmp = NULL;
		spin_unlock_irqrestore(&port->vio.lock, flags);
	}

	if (map_perm & LDC_MAP_W)
		memcpy(buf, req_buf, len);

	kfree(req_buf);

	return err;
}