cfg80211: rcu-ify rdev and wdev
Future code will need to look up rdev and wdev within atomic sections, but currently we need to lock a mutex for such lookups. Change the list handling for both to be RCU-safe so that we can look them up in rcu sections instead in the future. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -1,7 +1,7 @@
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/*
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* This is the linux wireless configuration interface.
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*
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* Copyright 2006-2009 Johannes Berg <johannes@sipsolutions.net>
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* Copyright 2006-2010 Johannes Berg <johannes@sipsolutions.net>
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*/
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#include <linux/if.h>
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@ -31,15 +31,10 @@ MODULE_AUTHOR("Johannes Berg");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("wireless configuration support");
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/* RCU might be appropriate here since we usually
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* only read the list, and that can happen quite
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* often because we need to do it for each command */
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/* RCU-protected (and cfg80211_mutex for writers) */
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LIST_HEAD(cfg80211_rdev_list);
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int cfg80211_rdev_list_generation;
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/*
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* This is used to protect the cfg80211_rdev_list
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*/
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DEFINE_MUTEX(cfg80211_mutex);
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/* for debugfs */
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@ -477,7 +472,7 @@ int wiphy_register(struct wiphy *wiphy)
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/* set up regulatory info */
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wiphy_update_regulatory(wiphy, NL80211_REGDOM_SET_BY_CORE);
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list_add(&rdev->list, &cfg80211_rdev_list);
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list_add_rcu(&rdev->list, &cfg80211_rdev_list);
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cfg80211_rdev_list_generation++;
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mutex_unlock(&cfg80211_mutex);
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@ -554,7 +549,8 @@ void wiphy_unregister(struct wiphy *wiphy)
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* it impossible to find from userspace.
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*/
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debugfs_remove_recursive(rdev->wiphy.debugfsdir);
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list_del(&rdev->list);
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list_del_rcu(&rdev->list);
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synchronize_rcu();
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/*
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* Try to grab rdev->mtx. If a command is still in progress,
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@ -670,7 +666,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
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INIT_LIST_HEAD(&wdev->event_list);
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spin_lock_init(&wdev->event_lock);
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mutex_lock(&rdev->devlist_mtx);
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list_add(&wdev->list, &rdev->netdev_list);
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list_add_rcu(&wdev->list, &rdev->netdev_list);
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rdev->devlist_generation++;
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/* can only change netns with wiphy */
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dev->features |= NETIF_F_NETNS_LOCAL;
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@ -782,13 +778,21 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
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*/
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if (!list_empty(&wdev->list)) {
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sysfs_remove_link(&dev->dev.kobj, "phy80211");
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list_del_init(&wdev->list);
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list_del_rcu(&wdev->list);
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rdev->devlist_generation++;
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#ifdef CONFIG_CFG80211_WEXT
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kfree(wdev->wext.keys);
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#endif
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}
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mutex_unlock(&rdev->devlist_mtx);
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/*
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* synchronise (so that we won't find this netdev
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* from other code any more) and then clear the list
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* head so that the above code can safely check for
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* !list_empty() to avoid double-cleanup.
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*/
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synchronize_rcu();
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INIT_LIST_HEAD(&wdev->list);
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break;
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case NETDEV_PRE_UP:
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if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))
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@ -1,7 +1,7 @@
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/*
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* Wireless configuration interface internals.
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*
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* Copyright 2006-2009 Johannes Berg <johannes@sipsolutions.net>
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* Copyright 2006-2010 Johannes Berg <johannes@sipsolutions.net>
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*/
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#ifndef __NET_WIRELESS_CORE_H
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#define __NET_WIRELESS_CORE_H
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@ -48,6 +48,7 @@ struct cfg80211_registered_device {
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/* associate netdev list */
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struct mutex devlist_mtx;
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/* protected by devlist_mtx or RCU */
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struct list_head netdev_list;
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int devlist_generation;
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int opencount; /* also protected by devlist_mtx */
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