Commit 024fcf5e authored by Johannes Berg's avatar Johannes Berg
Browse files

nl80211: use RCU to read regdom in reg get/dump 

Use RCU here to read the regdomain, this will allow us
to remove the RTNL locking from the setter.

Note in nl80211_get_reg_do() we still need the RTNL to
do the wiphy lookup.

Link: https://lore.kernel.org/r/20220214101820.5d4acbcf2a46.Ibfc91980439862125e983d9adeebaba73fe38e2d@changeid


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent b59fb546

net/wireless/nl80211.c

+17 −15
Original line number Diff line number Diff line
@@ -7948,6 +7948,7 @@ static int nl80211_get_reg_do(struct sk_buff *skb, struct genl_info *info) 
	struct cfg80211_registered_device *rdev;

	struct wiphy *wiphy = NULL;

	struct sk_buff *msg;

	int err = -EMSGSIZE;

	void *hdr;



	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
@@ -7966,34 +7967,35 @@ static int nl80211_get_reg_do(struct sk_buff *skb, struct genl_info *info) 


		rdev = cfg80211_get_dev_from_info(genl_info_net(info), info);

		if (IS_ERR(rdev)) {

			nlmsg_free(msg);

			rtnl_unlock();

			return PTR_ERR(rdev);

			err = PTR_ERR(rdev);

			goto nla_put_failure;

		}



		wiphy = &rdev->wiphy;

		self_managed = wiphy->regulatory_flags &

			       REGULATORY_WIPHY_SELF_MANAGED;



		rcu_read_lock();



		regdom = get_wiphy_regdom(wiphy);



		/* a self-managed-reg device must have a private regdom */

		if (WARN_ON(!regdom && self_managed)) {

			nlmsg_free(msg);

			rtnl_unlock();

			return -EINVAL;

			err = -EINVAL;

			goto nla_put_failure_rcu;

		}



		if (regdom &&

		    nla_put_u32(msg, NL80211_ATTR_WIPHY, get_wiphy_idx(wiphy)))

			goto nla_put_failure;

			goto nla_put_failure_rcu;

	} else {

		rcu_read_lock();

	}



	if (!wiphy && reg_last_request_cell_base() &&

	    nla_put_u32(msg, NL80211_ATTR_USER_REG_HINT_TYPE,

			NL80211_USER_REG_HINT_CELL_BASE))

		goto nla_put_failure;



	rcu_read_lock();

		goto nla_put_failure_rcu;



	if (!regdom)

		regdom = rcu_dereference(cfg80211_regdomain);
@@ -8013,7 +8015,7 @@ static int nl80211_get_reg_do(struct sk_buff *skb, struct genl_info *info) 
	rtnl_unlock();

put_failure:

	nlmsg_free(msg);

	return -EMSGSIZE;

	return err;

}



static int nl80211_send_regdom(struct sk_buff *msg, struct netlink_callback *cb,
@@ -8059,19 +8061,19 @@ static int nl80211_get_reg_dump(struct sk_buff *skb, 
	struct cfg80211_registered_device *rdev;

	int err, reg_idx, start = cb->args[2];



	rtnl_lock();

	rcu_read_lock();



	if (cfg80211_regdomain && start == 0) {

		err = nl80211_send_regdom(skb, cb, cb->nlh->nlmsg_seq,

					  NLM_F_MULTI, NULL,

					  rtnl_dereference(cfg80211_regdomain));

					  rcu_dereference(cfg80211_regdomain));

		if (err < 0)

			goto out_err;

	}



	/* the global regdom is idx 0 */

	reg_idx = 1;

	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {

	list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list) {

		regdom = get_wiphy_regdom(&rdev->wiphy);

		if (!regdom)

			continue;
@@ -8090,7 +8092,7 @@ static int nl80211_get_reg_dump(struct sk_buff *skb, 
	cb->args[2] = reg_idx;

	err = skb->len;

out_err:

	rtnl_unlock();

	rcu_read_unlock();

	return err;

}