regulatory: use RCU to protect last_request

This will allow making freq_reg_info() lock-free.

Acked-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 109 insertions, 90 deletions

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 9b64b201cdf1..2a7c3adf902f 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -82,7 +82,8 @@ static struct regulatory_request core_request_world = {
 };
 
 /* Receipt of information from last regulatory request */
-static struct regulatory_request *last_request = &core_request_world;
+static struct regulatory_request __rcu *last_request =
+        (void __rcu *)&core_request_world;
 
 /* To trigger userspace events */
 static struct platform_device *reg_pdev;
@@ -102,7 +103,7 @@ const struct ieee80211_regdomain __rcu *cfg80211_regdomain;
  * Protects static reg.c components:
  *      - cfg80211_regdomain (if not used with RCU)
  *      - cfg80211_world_regdom
- *      - last_request
+ *      - last_request (if not used with RCU)
  *      - reg_num_devs_support_basehint
  */
 static DEFINE_MUTEX(reg_mutex);
@@ -137,6 +138,12 @@ static void rcu_free_regdom(const struct ieee80211_regdomain *r)
         kfree_rcu((struct ieee80211_regdomain *)r, rcu_head);
 }
 
+static struct regulatory_request *get_last_request(void)
+{
+        return rcu_dereference_protected(last_request,
+                                         lockdep_is_held(&reg_mutex));
+}
+
 /* Used to queue up regulatory hints */
 static LIST_HEAD(reg_requests_list);
 static spinlock_t reg_requests_lock;
@@ -206,6 +213,7 @@ static void reset_regdomains(bool full_reset,
                              const struct ieee80211_regdomain *new_regdom)
 {
         const struct ieee80211_regdomain *r;
+        struct regulatory_request *lr;
 
         assert_reg_lock();
 
@@ -228,9 +236,10 @@ static void reset_regdomains(bool full_reset,
         if (!full_reset)
                 return;
 
-        if (last_request != &core_request_world)
-                kfree(last_request);
-        last_request = &core_request_world;
+        lr = get_last_request();
+        if (lr != &core_request_world && lr)
+                kfree_rcu(lr, rcu_head);
+        rcu_assign_pointer(last_request, &core_request_world);
 }
 
 /*
@@ -239,9 +248,11 @@ static void reset_regdomains(bool full_reset,
  */
 static void update_world_regdomain(const struct ieee80211_regdomain *rd)
 {
-        WARN_ON(!last_request);
+        struct regulatory_request *lr;
 
-        assert_reg_lock();
+        lr = get_last_request();
+
+        WARN_ON(!lr);
 
         reset_regdomains(false, rd);
 
@@ -448,15 +459,12 @@ static int call_crda(const char *alpha2)
 
 static bool reg_is_valid_request(const char *alpha2)
 {
-        assert_reg_lock();
+        struct regulatory_request *lr = get_last_request();
 
-        if (!last_request)
+        if (!lr || lr->processed)
                 return false;
 
-        if (last_request->processed)
-                return false;
-
-        return alpha2_equal(last_request->alpha2, alpha2);
+        return alpha2_equal(lr->alpha2, alpha2);
 }
 
 /* Sanity check on a regulatory rule */
@@ -746,15 +754,14 @@ int freq_reg_info(struct wiphy *wiphy, u32 center_freq,
                   const struct ieee80211_reg_rule **reg_rule)
 {
         const struct ieee80211_regdomain *regd;
-
-        assert_reg_lock();
+        struct regulatory_request *lr = get_last_request();
 
         /*
          * Follow the driver's regulatory domain, if present, unless a country
          * IE has been processed or a user wants to help complaince further
          */
-        if (last_request->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
-            last_request->initiator != NL80211_REGDOM_SET_BY_USER &&
+        if (lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
+            lr->initiator != NL80211_REGDOM_SET_BY_USER &&
             wiphy->regd)
                 regd = get_wiphy_regdom(wiphy);
         else
@@ -828,8 +835,9 @@ static void handle_channel(struct wiphy *wiphy,
         const struct ieee80211_power_rule *power_rule = NULL;
         const struct ieee80211_freq_range *freq_range = NULL;
         struct wiphy *request_wiphy = NULL;
+        struct regulatory_request *lr = get_last_request();
 
-        request_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
+        request_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);
 
         flags = chan->orig_flags;
 
@@ -862,7 +870,7 @@ static void handle_channel(struct wiphy *wiphy,
         if (freq_range->max_bandwidth_khz < MHZ_TO_KHZ(40))
                 bw_flags = IEEE80211_CHAN_NO_HT40;
 
-        if (last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
+        if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
             request_wiphy && request_wiphy == wiphy &&
             request_wiphy->flags & WIPHY_FLAG_STRICT_REGULATORY) {
                 /*
@@ -927,7 +935,7 @@ bool reg_last_request_cell_base(void)
         bool val;
 
         mutex_lock(&reg_mutex);
-        val = reg_request_cell_base(last_request);
+        val = reg_request_cell_base(get_last_request());
         mutex_unlock(&reg_mutex);
 
         return val;
@@ -938,10 +946,12 @@ bool reg_last_request_cell_base(void)
 static enum reg_request_treatment
 reg_ignore_cell_hint(struct regulatory_request *pending_request)
 {
+        struct regulatory_request *lr = get_last_request();
+
         if (!reg_num_devs_support_basehint)
                 return REG_REQ_IGNORE;
 
-        if (reg_request_cell_base(last_request) &&
+        if (reg_request_cell_base(lr) &&
             !regdom_changes(pending_request->alpha2))
                 return REG_REQ_ALREADY_SET;
 
@@ -969,7 +979,9 @@ static bool reg_dev_ignore_cell_hint(struct wiphy *wiphy)
 static bool ignore_reg_update(struct wiphy *wiphy,
                               enum nl80211_reg_initiator initiator)
 {
-        if (!last_request) {
+        struct regulatory_request *lr = get_last_request();
+
+        if (!lr) {
                 REG_DBG_PRINT("Ignoring regulatory request %s since last_request is not set\n",
                               reg_initiator_name(initiator));
                 return true;
@@ -988,13 +1000,13 @@ static bool ignore_reg_update(struct wiphy *wiphy,
          */
         if (wiphy->flags & WIPHY_FLAG_STRICT_REGULATORY && !wiphy->regd &&
             initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
-            !is_world_regdom(last_request->alpha2)) {
+            !is_world_regdom(lr->alpha2)) {
                 REG_DBG_PRINT("Ignoring regulatory request %s since the driver requires its own regulatory domain to be set first\n",
                               reg_initiator_name(initiator));
                 return true;
         }
 
-        if (reg_request_cell_base(last_request))
+        if (reg_request_cell_base(lr))
                 return reg_dev_ignore_cell_hint(wiphy);
 
         return false;
@@ -1080,12 +1092,12 @@ static bool reg_is_world_roaming(struct wiphy *wiphy)
 {
         const struct ieee80211_regdomain *cr = get_cfg80211_regdom();
         const struct ieee80211_regdomain *wr = get_wiphy_regdom(wiphy);
+        struct regulatory_request *lr = get_last_request();
 
         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 &&
+        if (lr && lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE &&
             wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY)
                 return true;
 
@@ -1184,13 +1196,12 @@ static void wiphy_update_regulatory(struct wiphy *wiphy,
                                     enum nl80211_reg_initiator initiator)
 {
         enum ieee80211_band band;
-
-        assert_reg_lock();
+        struct regulatory_request *lr = get_last_request();
 
         if (ignore_reg_update(wiphy, initiator))
                 return;
 
-        last_request->dfs_region = get_cfg80211_regdom()->dfs_region;
+        lr->dfs_region = get_cfg80211_regdom()->dfs_region;
 
         for (band = 0; band < IEEE80211_NUM_BANDS; band++)
                 handle_band(wiphy, initiator, wiphy->bands[band]);
@@ -1199,7 +1210,7 @@ static void wiphy_update_regulatory(struct wiphy *wiphy,
         reg_process_ht_flags(wiphy);
 
         if (wiphy->reg_notifier)
-                wiphy->reg_notifier(wiphy, last_request);
+                wiphy->reg_notifier(wiphy, lr);
 }
 
 static void update_all_wiphy_regulatory(enum nl80211_reg_initiator initiator)
@@ -1220,7 +1231,7 @@ static void update_all_wiphy_regulatory(enum nl80211_reg_initiator initiator)
                 if (initiator == NL80211_REGDOM_SET_BY_CORE &&
                     wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY &&
                     wiphy->reg_notifier)
-                        wiphy->reg_notifier(wiphy, last_request);
+                        wiphy->reg_notifier(wiphy, get_last_request());
         }
 }
 
@@ -1300,28 +1311,28 @@ get_reg_request_treatment(struct wiphy *wiphy,
                           struct regulatory_request *pending_request)
 {
         struct wiphy *last_wiphy = NULL;
+        struct regulatory_request *lr = get_last_request();
 
         /* All initial requests are respected */
-        if (!last_request)
+        if (!lr)
                 return REG_REQ_OK;
 
         switch (pending_request->initiator) {
         case NL80211_REGDOM_SET_BY_CORE:
                 return REG_REQ_OK;
         case NL80211_REGDOM_SET_BY_COUNTRY_IE:
-                if (reg_request_cell_base(last_request)) {
+                if (reg_request_cell_base(lr)) {
                         /* Trust a Cell base station over the AP's country IE */
                         if (regdom_changes(pending_request->alpha2))
                                 return REG_REQ_IGNORE;
                         return REG_REQ_ALREADY_SET;
                 }
 
-                last_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
+                last_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);
 
                 if (unlikely(!is_an_alpha2(pending_request->alpha2)))
                         return -EINVAL;
-                if (last_request->initiator ==
-                    NL80211_REGDOM_SET_BY_COUNTRY_IE) {
+                if (lr->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE) {
                         if (last_wiphy != wiphy) {
                                 /*
                                  * Two cards with two APs claiming different
@@ -1343,7 +1354,7 @@ get_reg_request_treatment(struct wiphy *wiphy,
                 }
                 return 0;
         case NL80211_REGDOM_SET_BY_DRIVER:
-                if (last_request->initiator == NL80211_REGDOM_SET_BY_CORE) {
+                if (lr->initiator == NL80211_REGDOM_SET_BY_CORE) {
                         if (regdom_changes(pending_request->alpha2))
                                 return REG_REQ_OK;
                         return REG_REQ_ALREADY_SET;
@@ -1354,7 +1365,7 @@ get_reg_request_treatment(struct wiphy *wiphy,
                  * back in or if you add a new device for which the previously
                  * loaded card also agrees on the regulatory domain.
                  */
-                if (last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
+                if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
                     !regdom_changes(pending_request->alpha2))
                         return REG_REQ_ALREADY_SET;
 
@@ -1363,26 +1374,26 @@ get_reg_request_treatment(struct wiphy *wiphy,
                 if (reg_request_cell_base(pending_request))
                         return reg_ignore_cell_hint(pending_request);
 
-                if (reg_request_cell_base(last_request))
+                if (reg_request_cell_base(lr))
                         return REG_REQ_IGNORE;
 
-                if (last_request->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE)
+                if (lr->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE)
                         return REG_REQ_INTERSECT;
                 /*
                  * If the user knows better the user should set the regdom
                  * to their country before the IE is picked up
                  */
-                if (last_request->initiator == NL80211_REGDOM_SET_BY_USER &&
-                    last_request->intersect)
+                if (lr->initiator == NL80211_REGDOM_SET_BY_USER &&
+                    lr->intersect)
                         return REG_REQ_IGNORE;
                 /*
                  * Process user requests only after previous user/driver/core
                  * requests have been processed
                  */
-                if ((last_request->initiator == NL80211_REGDOM_SET_BY_CORE ||
-                     last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER ||
-                     last_request->initiator == NL80211_REGDOM_SET_BY_USER) &&
-                    regdom_changes(last_request->alpha2))
+                if ((lr->initiator == NL80211_REGDOM_SET_BY_CORE ||
+                     lr->initiator == NL80211_REGDOM_SET_BY_DRIVER ||
+                     lr->initiator == NL80211_REGDOM_SET_BY_USER) &&
+                    regdom_changes(lr->alpha2))
                         return REG_REQ_IGNORE;
 
                 if (!regdom_changes(pending_request->alpha2))
@@ -1397,15 +1408,16 @@ get_reg_request_treatment(struct wiphy *wiphy,
 static void reg_set_request_processed(void)
 {
         bool need_more_processing = false;
+        struct regulatory_request *lr = get_last_request();
 
-        last_request->processed = true;
+        lr->processed = true;
 
         spin_lock(&reg_requests_lock);
         if (!list_empty(&reg_requests_list))
                 need_more_processing = true;
         spin_unlock(&reg_requests_lock);
 
-        if (last_request->initiator == NL80211_REGDOM_SET_BY_USER)
+        if (lr->initiator == NL80211_REGDOM_SET_BY_USER)
                 cancel_delayed_work(&reg_timeout);
 
         if (need_more_processing)
@@ -1432,6 +1444,7 @@ __regulatory_hint(struct wiphy *wiphy,
         const struct ieee80211_regdomain *regd;
         bool intersect = false;
         enum reg_request_treatment treatment;
+        struct regulatory_request *lr;
 
         treatment = get_reg_request_treatment(wiphy, pending_request);
 
@@ -1472,18 +1485,20 @@ __regulatory_hint(struct wiphy *wiphy,
         }
 
 new_request:
-        if (last_request != &core_request_world)
-                kfree(last_request);
+        lr = get_last_request();
+        if (lr != &core_request_world && lr)
+                kfree_rcu(lr, rcu_head);
 
-        last_request = pending_request;
-        last_request->intersect = intersect;
-        last_request->processed = false;
+        pending_request->intersect = intersect;
+        pending_request->processed = false;
+        rcu_assign_pointer(last_request, pending_request);
+        lr = pending_request;
 
         pending_request = NULL;
 
-        if (last_request->initiator == NL80211_REGDOM_SET_BY_USER) {
-                user_alpha2[0] = last_request->alpha2[0];
-                user_alpha2[1] = last_request->alpha2[1];
+        if (lr->initiator == NL80211_REGDOM_SET_BY_USER) {
+                user_alpha2[0] = lr->alpha2[0];
+                user_alpha2[1] = lr->alpha2[1];
         }
 
         /* When r == REG_REQ_INTERSECT we do need to call CRDA */
@@ -1494,13 +1509,13 @@ new_request:
                  * inform userspace we have processed the request
                  */
                 if (treatment == REG_REQ_ALREADY_SET) {
-                        nl80211_send_reg_change_event(last_request);
+                        nl80211_send_reg_change_event(lr);
                         reg_set_request_processed();
                 }
                 return treatment;
         }
 
-        if (call_crda(last_request->alpha2))
+        if (call_crda(lr->alpha2))
                 return REG_REQ_IGNORE;
         return REG_REQ_OK;
 }
@@ -1543,13 +1558,14 @@ static void reg_process_hint(struct regulatory_request *reg_request,
  */
 static void reg_process_pending_hints(void)
 {
-        struct regulatory_request *reg_request;
+        struct regulatory_request *reg_request, *lr;
 
         mutex_lock(&cfg80211_mutex);
         mutex_lock(&reg_mutex);
+        lr = get_last_request();
 
         /* When last_request->processed becomes true this will be rescheduled */
-        if (last_request && !last_request->processed) {
+        if (lr && !lr->processed) {
                 REG_DBG_PRINT("Pending regulatory request, waiting for it to be processed...\n");
                 goto out;
         }
@@ -1702,11 +1718,12 @@ void regulatory_hint_11d(struct wiphy *wiphy, enum ieee80211_band band,
 {
         char alpha2[2];
         enum environment_cap env = ENVIRON_ANY;
-        struct regulatory_request *request;
+        struct regulatory_request *request, *lr;
 
         mutex_lock(&reg_mutex);
+        lr = get_last_request();
 
-        if (unlikely(!last_request))
+        if (unlikely(!lr))
                 goto out;
 
         /* IE len must be evenly divisible by 2 */
@@ -1729,8 +1746,8 @@ void regulatory_hint_11d(struct wiphy *wiphy, enum ieee80211_band band,
          * We leave conflict resolution to the workqueue, where can hold
          * cfg80211_mutex.
          */
-        if (last_request->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&
-            last_request->wiphy_idx != WIPHY_IDX_INVALID)
+        if (lr->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&
+            lr->wiphy_idx != WIPHY_IDX_INVALID)
                 goto out;
 
         request = kzalloc(sizeof(struct regulatory_request), GFP_KERNEL);
@@ -2021,13 +2038,12 @@ static void print_dfs_region(u8 dfs_region)
 
 static void print_regdomain(const struct ieee80211_regdomain *rd)
 {
+        struct regulatory_request *lr = get_last_request();
 
         if (is_intersected_alpha2(rd->alpha2)) {
-                if (last_request->initiator ==
-                    NL80211_REGDOM_SET_BY_COUNTRY_IE) {
+                if (lr->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE) {
                         struct cfg80211_registered_device *rdev;
-                        rdev = cfg80211_rdev_by_wiphy_idx(
-                                last_request->wiphy_idx);
+                        rdev = cfg80211_rdev_by_wiphy_idx(lr->wiphy_idx);
                         if (rdev) {
                                 pr_info("Current regulatory domain updated by AP to: %c%c\n",
                                         rdev->country_ie_alpha2[0],
@@ -2042,7 +2058,7 @@ static void print_regdomain(const struct ieee80211_regdomain *rd)
                 if (is_unknown_alpha2(rd->alpha2))
                         pr_info("Regulatory domain changed to driver built-in settings (unknown country)\n");
                 else {
-                        if (reg_request_cell_base(last_request))
+                        if (reg_request_cell_base(lr))
                                 pr_info("Regulatory domain changed to country: %c%c by Cell Station\n",
                                         rd->alpha2[0], rd->alpha2[1]);
                         else
@@ -2067,11 +2083,10 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
         const struct ieee80211_regdomain *regd;
         const struct ieee80211_regdomain *intersected_rd = NULL;
         struct wiphy *request_wiphy;
+        struct regulatory_request *lr = get_last_request();
 
         /* Some basic sanity checks first */
 
-        assert_reg_lock();
-
         if (!reg_is_valid_request(rd->alpha2))
                 return -EINVAL;
 
@@ -2089,7 +2104,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
          * rd is non static (it means CRDA was present and was used last)
          * and the pending request came in from a country IE
          */
-        if (last_request->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE) {
+        if (lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE) {
                 /*
                  * If someone else asked us to change the rd lets only bother
                  * checking if the alpha2 changes if CRDA was already called
@@ -2111,16 +2126,16 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
                 return -EINVAL;
         }
 
-        request_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
+        request_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);
         if (!request_wiphy &&
-            (last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER ||
-             last_request->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE)) {
+            (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER ||
+             lr->initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE)) {
                 schedule_delayed_work(&reg_timeout, 0);
                 return -ENODEV;
         }
 
-        if (!last_request->intersect) {
-                if (last_request->initiator != NL80211_REGDOM_SET_BY_DRIVER) {
+        if (!lr->intersect) {
+                if (lr->initiator != NL80211_REGDOM_SET_BY_DRIVER) {
                         reset_regdomains(false, rd);
                         return 0;
                 }
@@ -2148,7 +2163,7 @@ 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) {
+        if (lr->initiator != NL80211_REGDOM_SET_BY_COUNTRY_IE) {
                 intersected_rd = regdom_intersect(rd, get_cfg80211_regdom());
                 if (!intersected_rd)
                         return -EINVAL;
@@ -2158,7 +2173,7 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
                  * However if a driver requested this specific regulatory
                  * domain we keep it for its private use
                  */
-                if (last_request->initiator == NL80211_REGDOM_SET_BY_DRIVER)
+                if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER)
                         rcu_assign_pointer(request_wiphy->regd, rd);
                 else
                         kfree(rd);
@@ -2181,9 +2196,11 @@ static int __set_regdom(const struct ieee80211_regdomain *rd)
  */
 int set_regdom(const struct ieee80211_regdomain *rd)
 {
+        struct regulatory_request *lr;
         int r;
 
         mutex_lock(&reg_mutex);
+        lr = get_last_request();
 
         /* Note that this doesn't update the wiphys, this is done below */
         r = __set_regdom(rd);
@@ -2196,18 +2213,17 @@ int set_regdom(const struct ieee80211_regdomain *rd)
         }
 
         /* This would make this whole thing pointless */
-        if (WARN_ON(!last_request->intersect &&
-                    rd != get_cfg80211_regdom())) {
+        if (WARN_ON(!lr->intersect && rd != get_cfg80211_regdom())) {
                 r = -EINVAL;
                 goto out;
         }
 
         /* update all wiphys now with the new established regulatory domain */
-        update_all_wiphy_regulatory(last_request->initiator);
+        update_all_wiphy_regulatory(lr->initiator);
 
         print_regdomain(get_cfg80211_regdom());
 
-        nl80211_send_reg_change_event(last_request);
+        nl80211_send_reg_change_event(lr);
 
         reg_set_request_processed();
 
@@ -2220,10 +2236,11 @@ int set_regdom(const struct ieee80211_regdomain *rd)
 #ifdef CONFIG_HOTPLUG
 int reg_device_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
-        if (last_request && !last_request->processed) {
+        struct regulatory_request *lr = get_last_request();
+
+        if (lr && !lr->processed) {
                 if (add_uevent_var(env, "COUNTRY=%c%c",
-                                   last_request->alpha2[0],
-                                   last_request->alpha2[1]))
+                                   lr->alpha2[0], lr->alpha2[1]))
                         return -ENOMEM;
         }
 
@@ -2252,8 +2269,10 @@ void wiphy_regulatory_register(struct wiphy *wiphy)
 void wiphy_regulatory_deregister(struct wiphy *wiphy)
 {
         struct wiphy *request_wiphy = NULL;
+        struct regulatory_request *lr;
 
         mutex_lock(&reg_mutex);
+        lr = get_last_request();
 
         if (!reg_dev_ignore_cell_hint(wiphy))
                 reg_num_devs_support_basehint--;
@@ -2261,14 +2280,14 @@ void wiphy_regulatory_deregister(struct wiphy *wiphy)
         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);
+        if (lr)
+                request_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);
 
         if (!request_wiphy || request_wiphy != wiphy)
                 goto out;
 
-        last_request->wiphy_idx = WIPHY_IDX_INVALID;
-        last_request->country_ie_env = ENVIRON_ANY;
+        lr->wiphy_idx = WIPHY_IDX_INVALID;
+        lr->country_ie_env = ENVIRON_ANY;
 out:
         mutex_unlock(&reg_mutex);
 }