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

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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 <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2022-02-14 10:18:20 +01:00
parent b59fb54611
commit 024fcf5efd
1 changed files with 17 additions and 15 deletions
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32
net/wireless/nl80211.c
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@ -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;
}