My patch titled
[PATCH] make cfg80211 manage wiphy netdev list
introduced a deadlock in cfg80211 when adding or removing interfaces.
The deadlock happens because I used the same mutex for making sure that
no two calls are in progress as for managing the list. This patch fixes
it by using a separate mutex for the list.
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
net/wireless/core.c | 10 ++++++----
net/wireless/core.h | 1 +
net/wireless/nl80211.c | 11 +++++++++--
3 files changed, 16 insertions(+), 6 deletions(-)
--- wireless-dev.orig/net/wireless/core.c 2007-02-28 14:55:22.406381760 +0100
+++ wireless-dev/net/wireless/core.c 2007-02-28 14:55:28.646381760 +0100
@@ -170,6 +170,7 @@ struct wiphy *wiphy_new(struct cfg80211_
mutex_unlock(&cfg80211_drv_mutex);
mutex_init(&drv->mtx);
+ mutex_init(&drv->devlist_mtx);
INIT_LIST_HEAD(&drv->netdev_list);
device_initialize(&drv->wiphy.dev);
@@ -228,6 +229,7 @@ EXPORT_SYMBOL(wiphy_unregister);
void cfg80211_dev_free(struct cfg80211_registered_device *drv)
{
mutex_destroy(&drv->mtx);
+ mutex_destroy(&drv->devlist_mtx);
kfree(drv);
}
@@ -251,20 +253,20 @@ static int cfg80211_netdev_notifier_call
switch (state) {
case NETDEV_REGISTER:
- mutex_lock(&rdev->mtx);
+ mutex_lock(&rdev->devlist_mtx);
list_add(&dev->ieee80211_ptr->list, &rdev->netdev_list);
if (sysfs_create_link(&dev->dev.kobj, &rdev->wiphy.dev.kobj,
"phy80211")) {
printk(KERN_ERR "wireless: failed to add phy80211 symlink to netdev!\n");
}
dev->ieee80211_ptr->netdev = dev;
- mutex_unlock(&rdev->mtx);
+ mutex_unlock(&rdev->devlist_mtx);
break;
case NETDEV_UNREGISTER:
- mutex_lock(&rdev->mtx);
+ mutex_lock(&rdev->devlist_mtx);
sysfs_remove_link(&dev->dev.kobj, "phy80211");
list_del(&dev->ieee80211_ptr->list);
- mutex_unlock(&rdev->mtx);
+ mutex_unlock(&rdev->devlist_mtx);
break;
}
--- wireless-dev.orig/net/wireless/core.h 2007-02-28 14:55:22.436381760 +0100
+++ wireless-dev/net/wireless/core.h 2007-02-28 14:55:28.646381760 +0100
@@ -25,6 +25,7 @@ struct cfg80211_registered_device {
int idx;
/* associate netdev list */
+ struct mutex devlist_mtx;
struct list_head netdev_list;
/* must be last because of the way we do wiphy_priv(),
--- wireless-dev.orig/net/wireless/nl80211.c 2007-02-28 14:55:22.376381760 +0100
+++ wireless-dev/net/wireless/nl80211.c 2007-02-28 14:55:28.646381760 +0100
@@ -248,10 +248,17 @@ static int nl80211_get_intfs(struct sk_b
}
array_idx = 1;
+ err = 0;
+ mutex_lock(&drv->devlist_mtx);
list_for_each_entry(wdev, &drv->netdev_list, list) {
- if (addifidx(wdev->netdev, msg, &array_idx))
- goto msg_free;
+ err = addifidx(wdev->netdev, msg, &array_idx);
+ if (err)
+ break;
}
+ mutex_unlock(&drv->devlist_mtx);
+ if (err)
+ goto msg_free;
+
nla_nest_end(msg, start);
genlmsg_end(msg, hdr);
-
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