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Commit 494ef20d authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

xen/pciback: Fine-grain the spinlocks and fix BUG: scheduling while atomic cases. 



We were using coarse spinlocks that could end up with a deadlock.
This patch fixes that and makes the spinlocks much more fine-grained.

We also drop be->watchding state spinlocks as they are already
guarded by the xenwatch_thread against multiple customers. Without
that we would trigger the BUG: scheduling while atomic.

Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 0513fe9e

drivers/xen/xen-pciback/passthrough.c

+6 −3
Original line number Diff line number Diff line
@@ -113,14 +113,14 @@ int pciback_publish_pci_roots(struct pciback_device *pdev, 
{

	int err = 0;

	struct passthrough_dev_data *dev_data = pdev->pci_dev_data;

	struct pci_dev_entry *dev_entry, *e;

	struct pci_dev_entry *dev_entry, *e, *tmp;

	struct pci_dev *dev;

	int found;

	unsigned int domain, bus;



	spin_lock(&dev_data->lock);



	list_for_each_entry(dev_entry, &dev_data->dev_list, list) {

	list_for_each_entry_safe(dev_entry, tmp, &dev_data->dev_list, list) {

		/* Only publish this device as a root if none of its

		 * parent bridges are exported

		 */
@@ -139,12 +139,15 @@ int pciback_publish_pci_roots(struct pciback_device *pdev, 
		bus = (unsigned int)dev_entry->dev->bus->number;



		if (!found) {

			spin_unlock(&dev_data->lock);

			err = publish_root_cb(pdev, domain, bus);

			if (err)

				break;

			spin_lock(&dev_data->lock);

		}

	}



	if (!err)

		spin_unlock(&dev_data->lock);



	return err;

drivers/xen/xen-pciback/xenbus.c

+15 −11
Original line number Diff line number Diff line
@@ -54,23 +54,29 @@ static void pciback_disconnect(struct pciback_device *pdev) 
		unbind_from_irqhandler(pdev->evtchn_irq, pdev);

		pdev->evtchn_irq = INVALID_EVTCHN_IRQ;

	}

	spin_unlock(&pdev->dev_lock);



	/* If the driver domain started an op, make sure we complete it

	 * before releasing the shared memory */



	/* Note, the workqueue does not use spinlocks at all.*/

	flush_workqueue(pciback_wq);



	spin_lock(&pdev->dev_lock);

	if (pdev->sh_info != NULL) {

		xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);

		pdev->sh_info = NULL;

	}



	spin_unlock(&pdev->dev_lock);



}



static void free_pdev(struct pciback_device *pdev)

{

	if (pdev->be_watching)

	if (pdev->be_watching) {

		unregister_xenbus_watch(&pdev->be_watch);

		pdev->be_watching = 0;

	}



	pciback_disconnect(pdev);
@@ -98,7 +104,10 @@ static int pciback_do_attach(struct pciback_device *pdev, int gnt_ref, 
				"Error mapping other domain page in ours.");

		goto out;

	}



	spin_lock(&pdev->dev_lock);

	pdev->sh_info = vaddr;

	spin_unlock(&pdev->dev_lock);



	err = bind_interdomain_evtchn_to_irqhandler(

		pdev->xdev->otherend_id, remote_evtchn, pciback_handle_event,
@@ -108,7 +117,10 @@ static int pciback_do_attach(struct pciback_device *pdev, int gnt_ref, 
				 "Error binding event channel to IRQ");

		goto out;

	}



	spin_lock(&pdev->dev_lock);

	pdev->evtchn_irq = err;

	spin_unlock(&pdev->dev_lock);

	err = 0;



	dev_dbg(&pdev->xdev->dev, "Attached!\n");
@@ -122,7 +134,6 @@ static int pciback_attach(struct pciback_device *pdev) 
	int gnt_ref, remote_evtchn;

	char *magic = NULL;



	spin_lock(&pdev->dev_lock);



	/* Make sure we only do this setup once */

	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
@@ -168,7 +179,6 @@ static int pciback_attach(struct pciback_device *pdev) 


	dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);

out:

	spin_unlock(&pdev->dev_lock);



	kfree(magic);
@@ -340,7 +350,6 @@ static int pciback_reconfigure(struct pciback_device *pdev) 
	char state_str[64];

	char dev_str[64];



	spin_lock(&pdev->dev_lock);



	dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
@@ -481,8 +490,6 @@ static int pciback_reconfigure(struct pciback_device *pdev) 
	}



out:

	spin_unlock(&pdev->dev_lock);



	return 0;

}
@@ -539,8 +546,6 @@ static int pciback_setup_backend(struct pciback_device *pdev) 
	char dev_str[64];

	char state_str[64];



	spin_lock(&pdev->dev_lock);



	/* It's possible we could get the call to setup twice, so make sure

	 * we're not already connected.

	 */
@@ -621,8 +626,6 @@ static int pciback_setup_backend(struct pciback_device *pdev) 
				 "Error switching to initialised state!");



out:

	spin_unlock(&pdev->dev_lock);



	if (!err)

		/* see if pcifront is already configured (if not, we'll wait) */

		pciback_attach(pdev);
@@ -669,6 +672,7 @@ static int pciback_xenbus_probe(struct xenbus_device *dev, 
				pciback_be_watch);

	if (err)

		goto out;



	pdev->be_watching = 1;



	/* We need to force a call to our callback here in case