Re: "usbip: Implement SG support to vhci-hcd and stub driver" causes a deadlock

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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On Wed, Dec 11, 2019 at 12:07:54PM +0900, Suwan Kim wrote:
> HCD should giveback URB to driver calling usb_hcd_giveback_urb().
> But in the case of transaction error, vhci_recv_ret_submit()
> terminates without giveback URB. So, I think the error path in
> usbip_recv_xbuff and usbip_recv_iso should unlink URB from ep and
> insert proper error code in urb->status that indicates error
> status to driver and handle giveback URB to driver.
> 
> Then hub_irq doesn't need to flush error URB.
> That will be helpful to graceful connection shutdown.
> 
> 
> static void vhci_recv_ret_submit(struct vhci_device *vdev,
> 				 struct usbip_header *pdu)
> ...
> ...
> 	if (usbip_recv_xbuff(ud, urb) < 0) {
> 		urb->status = -EPIPE;
> 		goto error;	// goto error path
> 	}
> 
> 	/* recv iso_packet_descriptor */
> 	if (usbip_recv_iso(ud, urb) < 0) {
> 		urb->status = -EPIPE;
> 		goto error;	// goto error path
> 	}
> ...
> ...
> error://error path
> 	spin_lock_irqsave(&vhci->lock, flags);
> 	usb_hcd_unlink_urb_from_ep(vhci_hcd_to_hcd(vhci_hcd), urb);
> 	spin_unlock_irqrestore(&vhci->lock, flags);
> 
> 	usb_hcd_giveback_urb(vhci_hcd_to_hcd(vhci_hcd), urb, urb->status);
> 
> 	usbip_dbg_vhci_rx("Leave\n");
> }

Yup, that works! Now the error is handled gracefully instead of hanging.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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