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Commit 5f2aa25e authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

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: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent c57199bc

net/wireless/core.c

+15 −11
Original line number Diff line number Diff line 
/*

 * This is the linux wireless configuration interface.

 *

 * Copyright 2006-2009		Johannes Berg <johannes@sipsolutions.net>

 * Copyright 2006-2010		Johannes Berg <johannes@sipsolutions.net>

 */



#include <linux/if.h>
@@ -31,15 +31,10 @@ MODULE_AUTHOR("Johannes Berg"); 
MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("wireless configuration support");



/* RCU might be appropriate here since we usually

 * only read the list, and that can happen quite

 * often because we need to do it for each command */

/* RCU-protected (and cfg80211_mutex for writers) */

LIST_HEAD(cfg80211_rdev_list);

int cfg80211_rdev_list_generation;



/*

 * This is used to protect the cfg80211_rdev_list

 */

DEFINE_MUTEX(cfg80211_mutex);



/* for debugfs */
@@ -477,7 +472,7 @@ int wiphy_register(struct wiphy *wiphy) 
	/* set up regulatory info */

	wiphy_update_regulatory(wiphy, NL80211_REGDOM_SET_BY_CORE);



	list_add(&rdev->list, &cfg80211_rdev_list);

	list_add_rcu(&rdev->list, &cfg80211_rdev_list);

	cfg80211_rdev_list_generation++;



	mutex_unlock(&cfg80211_mutex);
@@ -554,7 +549,8 @@ void wiphy_unregister(struct wiphy *wiphy) 
	 * it impossible to find from userspace.

	 */

	debugfs_remove_recursive(rdev->wiphy.debugfsdir);

	list_del(&rdev->list);

	list_del_rcu(&rdev->list);

	synchronize_rcu();



	/*

	 * Try to grab rdev->mtx. If a command is still in progress,
@@ -670,7 +666,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb, 
		INIT_LIST_HEAD(&wdev->event_list);

		spin_lock_init(&wdev->event_lock);

		mutex_lock(&rdev->devlist_mtx);

		list_add(&wdev->list, &rdev->netdev_list);

		list_add_rcu(&wdev->list, &rdev->netdev_list);

		rdev->devlist_generation++;

		/* can only change netns with wiphy */

		dev->features |= NETIF_F_NETNS_LOCAL;
@@ -782,13 +778,21 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb, 
		 */

		if (!list_empty(&wdev->list)) {

			sysfs_remove_link(&dev->dev.kobj, "phy80211");

			list_del_init(&wdev->list);

			list_del_rcu(&wdev->list);

			rdev->devlist_generation++;

#ifdef CONFIG_CFG80211_WEXT

			kfree(wdev->wext.keys);

#endif

		}

		mutex_unlock(&rdev->devlist_mtx);

		/*

		 * synchronise (so that we won't find this netdev

		 * from other code any more) and then clear the list

		 * head so that the above code can safely check for

		 * !list_empty() to avoid double-cleanup.

		 */

		synchronize_rcu();

		INIT_LIST_HEAD(&wdev->list);

		break;

	case NETDEV_PRE_UP:

		if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))

net/wireless/core.h

+2 −1
Original line number Diff line number Diff line 
/*

 * Wireless configuration interface internals.

 *

 * Copyright 2006-2009	Johannes Berg <johannes@sipsolutions.net>

 * Copyright 2006-2010	Johannes Berg <johannes@sipsolutions.net>

 */

#ifndef __NET_WIRELESS_CORE_H

#define __NET_WIRELESS_CORE_H
@@ -48,6 +48,7 @@ struct cfg80211_registered_device { 


	/* associate netdev list */

	struct mutex devlist_mtx;

	/* protected by devlist_mtx or RCU */

	struct list_head netdev_list;

	int devlist_generation;

	int opencount; /* also protected by devlist_mtx */