From 024fcf5efda73d95394ec7448bc9751e265fb18f Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 14 Feb 2022 10:18:20 +0100 Subject: [PATCH] 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: Johannes Berg --- net/wireless/nl80211.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 578bff9c378b..56ff332132f7 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -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 @@ nla_put_failure: 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; } -- 2.20.1