regulatory: use RCU to protect global and wiphy regdomains
To simplify the locking and not require cfg80211_mutex
(which nl80211 uses to access the global regdomain) and
also to make it possible for drivers to access their
wiphy->regd safely, use RCU to protect these pointers.
Acked-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 35541d6..9b64b20 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -95,15 +95,15 @@
* Central wireless core regulatory domains, we only need two,
* the current one and a world regulatory domain in case we have no
* information to give us an alpha2.
- * Protected by the cfg80211_mutex.
*/
-const struct ieee80211_regdomain *cfg80211_regdomain;
+const struct ieee80211_regdomain __rcu *cfg80211_regdomain;
/*
* Protects static reg.c components:
- * - cfg80211_world_regdom
- * - last_request
- * - reg_num_devs_support_basehint
+ * - cfg80211_regdomain (if not used with RCU)
+ * - cfg80211_world_regdom
+ * - last_request
+ * - reg_num_devs_support_basehint
*/
static DEFINE_MUTEX(reg_mutex);
@@ -118,6 +118,25 @@
lockdep_assert_held(®_mutex);
}
+static const struct ieee80211_regdomain *get_cfg80211_regdom(void)
+{
+ return rcu_dereference_protected(cfg80211_regdomain,
+ lockdep_is_held(®_mutex));
+}
+
+static const struct ieee80211_regdomain *get_wiphy_regdom(struct wiphy *wiphy)
+{
+ return rcu_dereference_protected(wiphy->regd,
+ lockdep_is_held(®_mutex));
+}
+
+static void rcu_free_regdom(const struct ieee80211_regdomain *r)
+{
+ if (!r)
+ return;
+ kfree_rcu((struct ieee80211_regdomain *)r, rcu_head);
+}
+
/* Used to queue up regulatory hints */
static LIST_HEAD(reg_requests_list);
static spinlock_t reg_requests_lock;
@@ -186,22 +205,25 @@
static void reset_regdomains(bool full_reset,
const struct ieee80211_regdomain *new_regdom)
{
- assert_cfg80211_lock();
+ const struct ieee80211_regdomain *r;
+
assert_reg_lock();
+ r = get_cfg80211_regdom();
+
/* avoid freeing static information or freeing something twice */
- if (cfg80211_regdomain == cfg80211_world_regdom)
- cfg80211_regdomain = NULL;
+ if (r == cfg80211_world_regdom)
+ r = NULL;
if (cfg80211_world_regdom == &world_regdom)
cfg80211_world_regdom = NULL;
- if (cfg80211_regdomain == &world_regdom)
- cfg80211_regdomain = NULL;
+ if (r == &world_regdom)
+ r = NULL;
- kfree(cfg80211_regdomain);
- kfree(cfg80211_world_regdom);
+ rcu_free_regdom(r);
+ rcu_free_regdom(cfg80211_world_regdom);
cfg80211_world_regdom = &world_regdom;
- cfg80211_regdomain = new_regdom;
+ rcu_assign_pointer(cfg80211_regdomain, new_regdom);
if (!full_reset)
return;
@@ -219,7 +241,6 @@
{
WARN_ON(!last_request);
- assert_cfg80211_lock();
assert_reg_lock();
reset_regdomains(false, rd);
@@ -280,11 +301,11 @@
static bool regdom_changes(const char *alpha2)
{
- assert_cfg80211_lock();
+ const struct ieee80211_regdomain *r = get_cfg80211_regdom();
- if (!cfg80211_regdomain)
+ if (!r)
return true;
- return !alpha2_equal(cfg80211_regdomain->alpha2, alpha2);
+ return !alpha2_equal(r->alpha2, alpha2);
}
/*
@@ -727,7 +748,6 @@
const struct ieee80211_regdomain *regd;
assert_reg_lock();
- assert_cfg80211_lock();
/*
* Follow the driver's regulatory domain, if present, unless a country
@@ -736,9 +756,9 @@
if (last_request->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
last_request->initiator != NL80211_REGDOM_SET_BY_USER &&
wiphy->regd)
- regd = wiphy->regd;
+ regd = get_wiphy_regdom(wiphy);
else
- regd = cfg80211_regdomain;
+ regd = get_cfg80211_regdom();
return freq_reg_info_regd(wiphy, center_freq, reg_rule, regd);
}
@@ -809,8 +829,6 @@
const struct ieee80211_freq_range *freq_range = NULL;
struct wiphy *request_wiphy = NULL;
- assert_cfg80211_lock();
-
request_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
flags = chan->orig_flags;
@@ -1060,15 +1078,17 @@
static bool reg_is_world_roaming(struct wiphy *wiphy)
{
- assert_cfg80211_lock();
+ const struct ieee80211_regdomain *cr = get_cfg80211_regdom();
+ const struct ieee80211_regdomain *wr = get_wiphy_regdom(wiphy);
- if (is_world_regdom(cfg80211_regdomain->alpha2) ||
- (wiphy->regd && is_world_regdom(wiphy->regd->alpha2)))
+ if (is_world_regdom(cr->alpha2) || (wr && is_world_regdom(wr->alpha2)))
return true;
+
if (last_request &&
last_request->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY)
return true;
+
return false;
}
@@ -1165,13 +1185,12 @@
{
enum ieee80211_band band;
- assert_cfg80211_lock();
assert_reg_lock();
if (ignore_reg_update(wiphy, initiator))
return;
- last_request->dfs_region = cfg80211_regdomain->dfs_region;
+ last_request->dfs_region = get_cfg80211_regdom()->dfs_region;
for (band = 0; band < IEEE80211_NUM_BANDS; band++)
handle_band(wiphy, initiator, wiphy->bands[band]);
@@ -1188,6 +1207,8 @@
struct cfg80211_registered_device *rdev;
struct wiphy *wiphy;
+ assert_cfg80211_lock();
+
list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
wiphy = &rdev->wiphy;
wiphy_update_regulatory(wiphy, initiator);
@@ -1402,7 +1423,7 @@
*
* Returns one of the different reg request treatment values.
*
- * Caller must hold &cfg80211_mutex and ®_mutex
+ * Caller must hold ®_mutex
*/
static enum reg_request_treatment
__regulatory_hint(struct wiphy *wiphy,
@@ -1412,20 +1433,18 @@
bool intersect = false;
enum reg_request_treatment treatment;
- assert_cfg80211_lock();
-
treatment = get_reg_request_treatment(wiphy, pending_request);
switch (treatment) {
case REG_REQ_INTERSECT:
if (pending_request->initiator ==
NL80211_REGDOM_SET_BY_DRIVER) {
- regd = reg_copy_regd(cfg80211_regdomain);
+ regd = reg_copy_regd(get_cfg80211_regdom());
if (IS_ERR(regd)) {
kfree(pending_request);
return PTR_ERR(regd);
}
- wiphy->regd = regd;
+ rcu_assign_pointer(wiphy->regd, regd);
}
intersect = true;
break;
@@ -1439,13 +1458,13 @@
*/
if (treatment == REG_REQ_ALREADY_SET &&
pending_request->initiator == NL80211_REGDOM_SET_BY_DRIVER) {
- regd = reg_copy_regd(cfg80211_regdomain);
+ regd = reg_copy_regd(get_cfg80211_regdom());
if (IS_ERR(regd)) {
kfree(pending_request);
return REG_REQ_IGNORE;
}
treatment = REG_REQ_ALREADY_SET;
- wiphy->regd = regd;
+ rcu_assign_pointer(wiphy->regd, regd);
goto new_request;
}
kfree(pending_request);
@@ -2051,6 +2070,8 @@
/* Some basic sanity checks first */
+ assert_reg_lock();
+
if (!reg_is_valid_request(rd->alpha2))
return -EINVAL;
@@ -2120,7 +2141,7 @@
if (IS_ERR(regd))
return PTR_ERR(regd);
- request_wiphy->regd = regd;
+ rcu_assign_pointer(request_wiphy->regd, regd);
reset_regdomains(false, rd);
return 0;
}
@@ -2128,7 +2149,7 @@
/* Intersection requires a bit more work */
if (last_request->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE) {
- intersected_rd = regdom_intersect(rd, cfg80211_regdomain);
+ intersected_rd = regdom_intersect(rd, get_cfg80211_regdom());
if (!intersected_rd)
return -EINVAL;
@@ -2138,7 +2159,7 @@
* domain we keep it for its private use
*/
if (last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER)
- request_wiphy->regd = rd;
+ rcu_assign_pointer(request_wiphy->regd, rd);
else
kfree(rd);
@@ -2156,14 +2177,12 @@
/*
* Use this call to set the current regulatory domain. Conflicts with
* multiple drivers can be ironed out later. Caller must've already
- * kmalloc'd the rd structure. Caller must hold cfg80211_mutex
+ * kmalloc'd the rd structure.
*/
int set_regdom(const struct ieee80211_regdomain *rd)
{
int r;
- assert_cfg80211_lock();
-
mutex_lock(®_mutex);
/* Note that this doesn't update the wiphys, this is done below */
@@ -2177,7 +2196,8 @@
}
/* This would make this whole thing pointless */
- if (WARN_ON(!last_request->intersect && rd != cfg80211_regdomain)) {
+ if (WARN_ON(!last_request->intersect &&
+ rd != get_cfg80211_regdom())) {
r = -EINVAL;
goto out;
}
@@ -2185,7 +2205,7 @@
/* update all wiphys now with the new established regulatory domain */
update_all_wiphy_regulatory(last_request->initiator);
- print_regdomain(cfg80211_regdomain);
+ print_regdomain(get_cfg80211_regdom());
nl80211_send_reg_change_event(last_request);
@@ -2238,7 +2258,8 @@
if (!reg_dev_ignore_cell_hint(wiphy))
reg_num_devs_support_basehint--;
- kfree(wiphy->regd);
+ rcu_free_regdom(get_wiphy_regdom(wiphy));
+ rcu_assign_pointer(wiphy->regd, NULL);
if (last_request)
request_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
@@ -2273,13 +2294,13 @@
reg_regdb_size_check();
- cfg80211_regdomain = cfg80211_world_regdom;
+ rcu_assign_pointer(cfg80211_regdomain, cfg80211_world_regdom);
user_alpha2[0] = '9';
user_alpha2[1] = '7';
/* We always try to get an update for the static regdomain */
- err = regulatory_hint_core(cfg80211_regdomain->alpha2);
+ err = regulatory_hint_core(cfg80211_world_regdom->alpha2);
if (err) {
if (err == -ENOMEM)
return err;
@@ -2313,10 +2334,8 @@
cancel_delayed_work_sync(®_timeout);
/* Lock to suppress warnings */
- mutex_lock(&cfg80211_mutex);
mutex_lock(®_mutex);
reset_regdomains(true, NULL);
- mutex_unlock(&cfg80211_mutex);
mutex_unlock(®_mutex);
dev_set_uevent_suppress(®_pdev->dev, true);