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regulatory: use RCU to protect global and wiphy regdomains

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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>
This commit is contained in:
Johannes Berg
2012-12-06 15:47:38 +01:00
parent 379b82f4c9
commit 458f4f9e96
5 changed files with 88 additions and 66 deletions
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113
net/wireless/reg.c
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@@ -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(&reg_mutex);
}
static const struct ieee80211_regdomain *get_cfg80211_regdom(void)
{
return rcu_dereference_protected(cfg80211_regdomain,
lockdep_is_held(&reg_mutex));
}
static const struct ieee80211_regdomain *get_wiphy_regdom(struct wiphy *wiphy)
{
return rcu_dereference_protected(wiphy->regd,
lockdep_is_held(&reg_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 @@ 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;
@@ -219,7 +241,6 @@ static void update_world_regdomain(const struct ieee80211_regdomain *rd)
{
WARN_ON(!last_request);
assert_cfg80211_lock();
assert_reg_lock();
reset_regdomains(false, rd);
@@ -280,11 +301,11 @@ 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);
}
/*
@@ -727,7 +748,6 @@ 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
@@ -736,9 +756,9 @@ 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);
}
@@ -809,8 +829,6 @@ 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;
@@ -1060,15 +1078,17 @@ 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;
}
@@ -1165,13 +1185,12 @@ 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]);
@@ -1188,6 +1207,8 @@ 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);
@@ -1402,7 +1423,7 @@ static void reg_set_request_processed(void)
*
* Returns one of the different reg request treatment values.
*
* Caller must hold &cfg80211_mutex and &reg_mutex
* Caller must hold &reg_mutex
*/
static enum reg_request_treatment
__regulatory_hint(struct wiphy *wiphy,
@@ -1412,20 +1433,18 @@ __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;
@@ -1439,13 +1458,13 @@ __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);
@@ -2051,6 +2070,8 @@ 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;
@@ -2120,7 +2141,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
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 @@ 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;
@@ -2138,7 +2159,7 @@ 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);
@@ -2156,14 +2177,12 @@ 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(&reg_mutex);
/* Note that this doesn't update the wiphys, this is done below */
@@ -2177,7 +2196,8 @@ 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;
}
@@ -2185,7 +2205,7 @@ 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);
@@ -2238,7 +2258,8 @@ 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);
@@ -2273,13 +2294,13 @@ 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;
@@ -2313,10 +2334,8 @@ void regulatory_exit(void)
cancel_delayed_work_sync(&reg_timeout);
/* Lock to suppress warnings */
mutex_lock(&cfg80211_mutex);
mutex_lock(&reg_mutex);
reset_regdomains(true, NULL);
mutex_unlock(&cfg80211_mutex);
mutex_unlock(&reg_mutex);
dev_set_uevent_suppress(&reg_pdev->dev, true);