[WIRELESS] cfg80211: Clarify locking comment.

This patch clarifies the comment about locking in wiphy_unregister.

Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: John W. Linville <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Johannes Berg 2007-04-26 20:51:12 -07:00 • committed by David S. Miller
commit f16bfc1c09

View file

@ -91,7 +91,6 @@ int wiphy_register(struct wiphy *wiphy)
mutex_lock(&cfg80211_drv_mutex);
res = device_add(&drv->wiphy.dev);
if (res)
goto out_unlock;
@ -114,14 +113,26 @@ void wiphy_unregister(struct wiphy *wiphy)
{
struct cfg80211_registered_device *drv = wiphy_to_dev(wiphy);
/* protect the device list */
mutex_lock(&cfg80211_drv_mutex);
/* hold registered driver mutex during list removal as well
* to make sure no commands are in progress at the moment */
BUG_ON(!list_empty(&drv->netdev_list));
/*
* Try to grab drv->mtx. If a command is still in progress,
* hopefully the driver will refuse it since it's tearing
* down the device already. We wait for this command to complete
* before unlinking the item from the list.
* Note: as codified by the BUG_ON above we cannot get here if
* a virtual interface is still associated. Hence, we can only
* get to lock contention here if userspace issues a command
* that identified the hardware by wiphy index.
*/
mutex_lock(&drv->mtx);
list_del(&drv->list);
/* unlock again before freeing */
mutex_unlock(&drv->mtx);
list_del(&drv->list);
device_del(&drv->wiphy.dev);
debugfs_remove(drv->wiphy.debugfsdir);