On Fri, Mar 12, 2010 at 11:25:21AM -0700, Ky Srinivasan wrote:
> The attached patch fixes some bugs in usbfront.
>
What kernel version is this patch against? linux-2.6.18-xen?
-- Pasi
> Signed-off-by: K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>
>
>
>
>
> Bug#584218: Fix a scheduling race in usbfront. Create the thread only after
> we
> are connected. The current code schedules the thread at a point where the
> communication rings are not initialized yet.
>
> Signed-off-by: K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>
>
> Index: linux/drivers/xen/usbfront/xenbus.c
> ===================================================================
> --- linux.orig/drivers/xen/usbfront/xenbus.c 2010-03-10 12:10:58.000000000
> -0700
> +++ linux/drivers/xen/usbfront/xenbus.c 2010-03-10 12:17:24.000000000
> -0700
> @@ -192,11 +192,23 @@ static int connect(struct xenbus_device
> usbif_conn_request_t *req;
> int i, idx, err;
> int notify;
> + char name[TASK_COMM_LEN];
> + struct usb_hcd *hcd;
> +
> + hcd = info_to_hcd(info);
> + snprintf(name, TASK_COMM_LEN, "xenhcd.%d", hcd->self.busnum);
>
> err = talk_to_backend(dev, info);
> if (err)
> return err;
>
> + info->kthread = kthread_run(xenhcd_schedule, info, name);
> + if (IS_ERR(info->kthread)) {
> + err = PTR_ERR(info->kthread);
> + info->kthread = NULL;
> + xenbus_dev_fatal(dev, err, "Error creating thread");
> + return err;
> + }
> /* prepare ring for hotplug notification */
> for (idx = 0, i = 0; i < USB_CONN_RING_SIZE; i++) {
> req = RING_GET_REQUEST(&info->conn_ring, idx);
> @@ -274,7 +286,6 @@ static int usbfront_probe(struct xenbus_
> int err;
> struct usb_hcd *hcd;
> struct usbfront_info *info;
> - char name[TASK_COMM_LEN];
>
> if (usb_disabled())
> return -ENODEV;
> @@ -298,13 +309,6 @@ static int usbfront_probe(struct xenbus_
> }
>
> init_waitqueue_head(&info->wq);
> - snprintf(name, TASK_COMM_LEN, "xenhcd.%d", hcd->self.busnum);
> - info->kthread = kthread_run(xenhcd_schedule, info, name);
> - if (IS_ERR(info->kthread)) {
> - err = PTR_ERR(info->kthread);
> - info->kthread = NULL;
> - goto fail;
> - }
>
> return 0;
>
> @@ -343,8 +347,8 @@ static void backend_changed(struct xenbu
> case XenbusStateInitWait:
> if (dev->state != XenbusStateInitialising)
> break;
> - connect(dev);
> - xenbus_switch_state(dev, XenbusStateConnected);
> + if (!connect(dev))
> + xenbus_switch_state(dev, XenbusStateConnected);
> break;
>
> case XenbusStateClosing:
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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