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wifi: nl80211: don't take rtnl for most dumps

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Most (wdev-related) dumps also take RTNL just for lookup.
Apply the same logic as for pre_doit() in the previous
commit to avoid the RTNL. Since I refactored the checks
there into a helper to use here, it even simplifies the
code.

Link: https://patch.msgid.link/20261006120655.37954ad94c77.Ica4719b0054c949abf2528d9c4c13a5d6b7a1a49@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2026-10-06 12:04:03 +02:00
parent 8e3d9039d2
commit 197d5f64e3
1 changed files with 23 additions and 44 deletions
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67
net/wireless/nl80211.c
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@ -1304,6 +1304,8 @@ static int nl80211_prepare_wdev_dump(struct netlink_callback *cb,
struct wireless_dev **wdev,
struct nlattr **attrbuf)
{
struct net *netns = sock_net(cb->skb->sk);
u32 wdev_id;
int err;
if (!cb->args[0]) {
@ -1325,61 +1327,38 @@ static int nl80211_prepare_wdev_dump(struct netlink_callback *cb,
return err;
}
rtnl_lock();
*wdev = __cfg80211_wdev_from_attrs(NULL, sock_net(cb->skb->sk),
attrbuf);
rcu_read_lock();
*wdev = __cfg80211_wdev_from_attrs(NULL, netns, attrbuf);
kfree(attrbuf_free);
if (IS_ERR(*wdev)) {
rtnl_unlock();
rcu_read_unlock();
return PTR_ERR(*wdev);
}
*rdev = wiphy_to_rdev((*wdev)->wiphy);
mutex_lock(&(*rdev)->wiphy.mtx);
rtnl_unlock();
/* 0 is the first index - add 1 to parse only once */
cb->args[0] = (*rdev)->wiphy_idx + 1;
cb->args[1] = (*wdev)->identifier;
wdev_id = (*wdev)->identifier;
} else {
/* subtract the 1 again here */
struct wiphy *wiphy;
struct wireless_dev *tmp;
rtnl_lock();
wiphy = wiphy_idx_to_wiphy(cb->args[0] - 1);
if (!wiphy) {
rtnl_unlock();
rcu_read_lock();
*rdev = cfg80211_rdev_by_wiphy_idx(cb->args[0] - 1);
if (!*rdev) {
rcu_read_unlock();
return -ENODEV;
}
/*
* The first invocation validated the wdev's netns against
* the caller via __cfg80211_wdev_from_attrs(). The wiphy
* may have moved netns between dumpit invocations (via
* NL80211_CMD_SET_WIPHY_NETNS), so re-check here.
*/
if (!net_eq(wiphy_net(wiphy), sock_net(cb->skb->sk))) {
rtnl_unlock();
return -ENODEV;
}
*rdev = wiphy_to_rdev(wiphy);
*wdev = NULL;
list_for_each_entry(tmp, &(*rdev)->wiphy.wdev_list, list) {
if (tmp->identifier == cb->args[1]) {
*wdev = tmp;
break;
}
}
if (!*wdev) {
rtnl_unlock();
return -ENODEV;
}
mutex_lock(&(*rdev)->wiphy.mtx);
rtnl_unlock();
wdev_id = cb->args[1];
}
get_device(&(*rdev)->wiphy.dev);
rcu_read_unlock();
/* things may have changed since the lookup or the last dumpit call */
*wdev = nl80211_lock_and_recheck(*rdev, netns, wdev_id);
if (IS_ERR(*wdev))
return PTR_ERR(*wdev);
/* 0 is the first index - add 1 to parse only once */
cb->args[0] = (*rdev)->wiphy_idx + 1;
cb->args[1] = wdev_id;
return 0;
}