USB: HWA: fix device probe failure
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>
diff --git a/drivers/usb/host/hwa-hc.c b/drivers/usb/host/hwa-hc.c
index 4af750e..483990c 100644
--- a/drivers/usb/host/hwa-hc.c
+++ b/drivers/usb/host/hwa-hc.c
@@ -683,12 +683,9 @@
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 @@
/* 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;
diff --git a/drivers/usb/wusbcore/mmc.c b/drivers/usb/wusbcore/mmc.c
index 021467f..b71760c 100644
--- a/drivers/usb/wusbcore/mmc.c
+++ b/drivers/usb/wusbcore/mmc.c
@@ -195,6 +195,7 @@
struct device *dev = wusbhc->dev;
WARN_ON(wusbhc->wuie_host_info != NULL);
+ BUG_ON(wusbhc->uwb_rc == NULL);
result = wusbhc_rsv_establish(wusbhc);
if (result < 0) {
@@ -276,12 +277,38 @@
}
wusbhc->chid = *chid;
}
+
+ /* register with UWB if we haven't already since we are about to start
+ the radio. */
+ if ((chid) && (wusbhc->uwb_rc == NULL)) {
+ wusbhc->uwb_rc = uwb_rc_get_by_grandpa(wusbhc->dev->parent);
+ if (wusbhc->uwb_rc == NULL) {
+ result = -ENODEV;
+ dev_err(wusbhc->dev, "Cannot get associated UWB Host Controller\n");
+ goto error_rc_get;
+ }
+
+ result = wusbhc_pal_register(wusbhc);
+ if (result < 0) {
+ dev_err(wusbhc->dev, "Cannot register as a UWB PAL\n");
+ goto error_pal_register;
+ }
+ }
mutex_unlock(&wusbhc->mutex);
if (chid)
result = uwb_radio_start(&wusbhc->pal);
else
uwb_radio_stop(&wusbhc->pal);
+
+ return result;
+
+error_pal_register:
+ uwb_rc_put(wusbhc->uwb_rc);
+ wusbhc->uwb_rc = NULL;
+error_rc_get:
+ mutex_unlock(&wusbhc->mutex);
+
return result;
}
EXPORT_SYMBOL_GPL(wusbhc_chid_set);
diff --git a/drivers/usb/wusbcore/pal.c b/drivers/usb/wusbcore/pal.c
index d0b172c..59e100c 100644
--- a/drivers/usb/wusbcore/pal.c
+++ b/drivers/usb/wusbcore/pal.c
@@ -45,10 +45,11 @@
}
/**
- * wusbhc_pal_register - unregister the WUSB HC as a UWB PAL
+ * wusbhc_pal_unregister - unregister the WUSB HC as a UWB PAL
* @wusbhc: the WUSB HC
*/
void wusbhc_pal_unregister(struct wusbhc *wusbhc)
{
- uwb_pal_unregister(&wusbhc->pal);
+ if (wusbhc->uwb_rc)
+ uwb_pal_unregister(&wusbhc->pal);
}
diff --git a/drivers/usb/wusbcore/reservation.c b/drivers/usb/wusbcore/reservation.c
index 6f4fafd..ead79f7 100644
--- a/drivers/usb/wusbcore/reservation.c
+++ b/drivers/usb/wusbcore/reservation.c
@@ -80,6 +80,9 @@
struct uwb_dev_addr bcid;
int ret;
+ if (rc == NULL)
+ return -ENODEV;
+
rsv = uwb_rsv_create(rc, wusbhc_rsv_complete_cb, wusbhc);
if (rsv == NULL)
return -ENOMEM;
diff --git a/drivers/usb/wusbcore/wusbhc.c b/drivers/usb/wusbcore/wusbhc.c
index e712af3..742c607 100644
--- a/drivers/usb/wusbcore/wusbhc.c
+++ b/drivers/usb/wusbcore/wusbhc.c
@@ -325,13 +325,7 @@
goto error_create_attr_group;
}
- result = wusbhc_pal_register(wusbhc);
- if (result < 0)
- goto error_pal_register;
return 0;
-
-error_pal_register:
- sysfs_remove_group(wusbhc_kobj(wusbhc), &wusbhc_attr_group);
error_create_attr_group:
return result;
}
@@ -457,7 +451,8 @@
*/
void wusbhc_reset_all(struct wusbhc *wusbhc)
{
- uwb_rc_reset_all(wusbhc->uwb_rc);
+ if (wusbhc->uwb_rc)
+ uwb_rc_reset_all(wusbhc->uwb_rc);
}
EXPORT_SYMBOL_GPL(wusbhc_reset_all);
diff --git a/drivers/uwb/pal.c b/drivers/uwb/pal.c
index 8ee7d90..690577d 100644
--- a/drivers/uwb/pal.c
+++ b/drivers/uwb/pal.c
@@ -44,10 +44,12 @@
int ret;
if (pal->device) {
+ /* create a link to the uwb_rc in the PAL device's directory. */
ret = sysfs_create_link(&pal->device->kobj,
&rc->uwb_dev.dev.kobj, "uwb_rc");
if (ret < 0)
return ret;
+ /* create a link to the PAL in the UWB device's directory. */
ret = sysfs_create_link(&rc->uwb_dev.dev.kobj,
&pal->device->kobj, pal->name);
if (ret < 0) {
diff --git a/drivers/uwb/uwb-internal.h b/drivers/uwb/uwb-internal.h
index a7494bf1..9a103b1 100644
--- a/drivers/uwb/uwb-internal.h
+++ b/drivers/uwb/uwb-internal.h
@@ -55,7 +55,8 @@
static inline void __uwb_rc_put(struct uwb_rc *rc)
{
- uwb_dev_put(&rc->uwb_dev);
+ if (rc)
+ uwb_dev_put(&rc->uwb_dev);
}
extern int uwb_rc_reset(struct uwb_rc *rc);
