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USB: HWA: fix device probe failure

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This patch fixes a race condition that caused the HWA_HC interface probe
function to occasionally fail.  The HWA_HC would attempt to register
itself with the HWA_RC by searching for a uwb_rc class device with the
same parent device ptr.  If the probe function for the HWA_RC interface
had yet to run, the uwb_rc class device would not have been created
causing the look up to fail and the HWA_HC probe function to return an
error causing the device to be unusable.

The fix is for the HWA to delay registering with the HWA_RC until
receiving the command from userspace to start the wireless channel.  It
is the responsibility of userspace to ensure that the uwb_rc class
device has been created before starting the HWA channel.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Pugliese
2013-06-24 14:26:35 -05:00
committed by Greg Kroah-Hartman
parent 6e6581e0a9
commit a899575191
7 changed files with 42 additions and 18 deletions
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11
drivers/usb/host/hwa-hc.c
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@@ -683,12 +683,9 @@ static int hwahc_create(struct hwahc *hwahc, struct usb_interface *iface)
wa->usb_dev = usb_get_dev(usb_dev); /* bind the USB device */
wa->usb_iface = usb_get_intf(iface);
wusbhc->dev = dev;
wusbhc->uwb_rc = uwb_rc_get_by_grandpa(iface->dev.parent);
if (wusbhc->uwb_rc == NULL) {
result = -ENODEV;
dev_err(dev, "Cannot get associated UWB Host Controller\n");
goto error_rc_get;
}
/* defer getting the uwb_rc handle until it is needed since it
* may not have been registered by the hwa_rc driver yet. */
wusbhc->uwb_rc = NULL;
result = wa_fill_descr(wa); /* Get the device descriptor */
if (result < 0)
goto error_fill_descriptor;
@@ -731,8 +728,6 @@ error_wusbhc_create:
/* WA Descr fill allocs no resources */
error_security_create:
error_fill_descriptor:
uwb_rc_put(wusbhc->uwb_rc);
error_rc_get:
usb_put_intf(iface);
usb_put_dev(usb_dev);
return result;