From: Johannes Berg <johannes.berg@xxxxxxxxx>
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.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/net/cfg80211.h | 2 +-
include/net/regulatory.h | 2 +
net/wireless/nl80211.c | 36 +++++++--------
net/wireless/reg.c | 113 +++++++++++++++++++++++++++--------------------
net/wireless/reg.h | 2 +-
5 files changed, 88 insertions(+), 67 deletions(-)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 84fcb10..461d979 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2369,7 +2369,7 @@ struct wiphy {
/* fields below are read-only, assigned by cfg80211 */
- const struct ieee80211_regdomain *regd;
+ const struct ieee80211_regdomain __rcu *regd;
/* the item in /sys/class/ieee80211/ points to this,
* you need use set_wiphy_dev() (see below) */
diff --git a/include/net/regulatory.h b/include/net/regulatory.h
index 7dcaa27..96b0f07 100644
--- a/include/net/regulatory.h
+++ b/include/net/regulatory.h
@@ -18,6 +18,7 @@
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
+#include <linux/rcupdate.h>
/**
* enum environment_cap - Environment parsed from country IE
@@ -101,6 +102,7 @@ struct ieee80211_reg_rule {
};
struct ieee80211_regdomain {
+ struct rcu_head rcu_head;
u32 n_reg_rules;
char alpha2[2];
u8 dfs_region;
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 370cd31..dd3df5c 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3811,12 +3811,8 @@ static int nl80211_req_set_reg(struct sk_buff *skb, struct genl_info *info)
* window between nl80211_init() and regulatory_init(), if that is
* even possible.
*/
- mutex_lock(&cfg80211_mutex);
- if (unlikely(!cfg80211_regdomain)) {
- mutex_unlock(&cfg80211_mutex);
+ if (unlikely(!rcu_access_pointer(cfg80211_regdomain)))
return -EINPROGRESS;
- }
- mutex_unlock(&cfg80211_mutex);
if (!info->attrs[NL80211_ATTR_REG_ALPHA2])
return -EINVAL;
@@ -4176,6 +4172,7 @@ static int nl80211_update_mesh_config(struct sk_buff *skb,
static int nl80211_get_reg(struct sk_buff *skb, struct genl_info *info)
{
+ const struct ieee80211_regdomain *regdom;
struct sk_buff *msg;
void *hdr = NULL;
struct nlattr *nl_reg_rules;
@@ -4198,35 +4195,36 @@ static int nl80211_get_reg(struct sk_buff *skb, struct genl_info *info)
if (!hdr)
goto put_failure;
- if (nla_put_string(msg, NL80211_ATTR_REG_ALPHA2,
- cfg80211_regdomain->alpha2) ||
- (cfg80211_regdomain->dfs_region &&
- nla_put_u8(msg, NL80211_ATTR_DFS_REGION,
- cfg80211_regdomain->dfs_region)))
- goto nla_put_failure;
+ rcu_read_lock();
+ regdom = rcu_dereference(cfg80211_regdomain);
+
+ if (nla_put_string(msg, NL80211_ATTR_REG_ALPHA2, regdom->alpha2) ||
+ (regdom->dfs_region &&
+ nla_put_u8(msg, NL80211_ATTR_DFS_REGION, regdom->dfs_region)))
+ goto nla_put_failure_rcu;
if (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;
+ goto nla_put_failure_rcu;
nl_reg_rules = nla_nest_start(msg, NL80211_ATTR_REG_RULES);
if (!nl_reg_rules)
- goto nla_put_failure;
+ goto nla_put_failure_rcu;
- for (i = 0; i < cfg80211_regdomain->n_reg_rules; i++) {
+ for (i = 0; i < regdom->n_reg_rules; i++) {
struct nlattr *nl_reg_rule;
const struct ieee80211_reg_rule *reg_rule;
const struct ieee80211_freq_range *freq_range;
const struct ieee80211_power_rule *power_rule;
- reg_rule = &cfg80211_regdomain->reg_rules[i];
+ reg_rule = ®dom->reg_rules[i];
freq_range = ®_rule->freq_range;
power_rule = ®_rule->power_rule;
nl_reg_rule = nla_nest_start(msg, i);
if (!nl_reg_rule)
- goto nla_put_failure;
+ goto nla_put_failure_rcu;
if (nla_put_u32(msg, NL80211_ATTR_REG_RULE_FLAGS,
reg_rule->flags) ||
@@ -4240,10 +4238,11 @@ static int nl80211_get_reg(struct sk_buff *skb, struct genl_info *info)
power_rule->max_antenna_gain) ||
nla_put_u32(msg, NL80211_ATTR_POWER_RULE_MAX_EIRP,
power_rule->max_eirp))
- goto nla_put_failure;
+ goto nla_put_failure_rcu;
nla_nest_end(msg, nl_reg_rule);
}
+ rcu_read_unlock();
nla_nest_end(msg, nl_reg_rules);
@@ -4251,7 +4250,8 @@ static int nl80211_get_reg(struct sk_buff *skb, struct genl_info *info)
err = genlmsg_reply(msg, info);
goto out;
-nla_put_failure:
+nla_put_failure_rcu:
+ rcu_read_unlock();
genlmsg_cancel(msg, hdr);
put_failure:
nlmsg_free(msg);
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index ff5ac4a..6082c68 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -95,15 +95,15 @@ static struct device_type reg_device_type = {
* 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 @@ static inline void assert_reg_lock(void)
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;
@@ -187,22 +206,25 @@ MODULE_PARM_DESC(ieee80211_regdom, "IEEE 802.11 regulatory domain code");
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;
@@ -220,7 +242,6 @@ static void update_world_regdomain(const struct ieee80211_regdomain *rd)
{
WARN_ON(!last_request);
- assert_cfg80211_lock();
assert_reg_lock();
reset_regdomains(false, rd);
@@ -281,11 +302,11 @@ static bool alpha2_equal(const char *alpha2_x, const char *alpha2_y)
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);
}
/*
@@ -728,7 +749,6 @@ int freq_reg_info(struct wiphy *wiphy, u32 center_freq,
const struct ieee80211_regdomain *regd;
assert_reg_lock();
- assert_cfg80211_lock();
/*
* Follow the driver's regulatory domain, if present, unless a country
@@ -737,9 +757,9 @@ int freq_reg_info(struct wiphy *wiphy, u32 center_freq,
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);
}
@@ -810,8 +830,6 @@ static void handle_channel(struct wiphy *wiphy,
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;
@@ -1061,15 +1079,17 @@ static void wiphy_update_beacon_reg(struct wiphy *wiphy)
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;
}
@@ -1166,13 +1186,12 @@ static void wiphy_update_regulatory(struct wiphy *wiphy,
{
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]);
@@ -1189,6 +1208,8 @@ static void update_all_wiphy_regulatory(enum nl80211_reg_initiator initiator)
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);
@@ -1403,7 +1424,7 @@ static void reg_set_request_processed(void)
*
* 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,
@@ -1413,20 +1434,18 @@ __regulatory_hint(struct wiphy *wiphy,
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;
@@ -1440,13 +1459,13 @@ __regulatory_hint(struct wiphy *wiphy,
*/
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);
@@ -2052,6 +2071,8 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
/* Some basic sanity checks first */
+ assert_reg_lock();
+
if (!reg_is_valid_request(rd->alpha2))
return -EINVAL;
@@ -2123,7 +2144,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
return PTR_ERR(regd);
}
- request_wiphy->regd = regd;
+ rcu_assign_pointer(request_wiphy->regd, regd);
reset_regdomains(false, rd);
return 0;
}
@@ -2131,7 +2152,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
/* 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;
@@ -2141,7 +2162,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
* 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);
@@ -2159,14 +2180,12 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
/*
* 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 */
@@ -2180,7 +2199,8 @@ int set_regdom(const struct ieee80211_regdomain *rd)
}
/* 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;
}
@@ -2188,7 +2208,7 @@ int set_regdom(const struct ieee80211_regdomain *rd)
/* 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);
@@ -2241,7 +2261,8 @@ void wiphy_regulatory_deregister(struct wiphy *wiphy)
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);
@@ -2276,13 +2297,13 @@ int __init regulatory_init(void)
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;
@@ -2316,10 +2337,8 @@ void regulatory_exit(void)
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);
diff --git a/net/wireless/reg.h b/net/wireless/reg.h
index d391b50..af2d5f8 100644
--- a/net/wireless/reg.h
+++ b/net/wireless/reg.h
@@ -16,7 +16,7 @@
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
-extern const struct ieee80211_regdomain *cfg80211_regdomain;
+extern const struct ieee80211_regdomain __rcu *cfg80211_regdomain;
bool is_world_regdom(const char *alpha2);
bool reg_supported_dfs_region(u8 dfs_region);
--
1.8.0
--
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