wifi: cfg80211: keep bss_lock held when informing

It is reasonable to hold bss_lock for a little bit longer after
cfg80211_bss_update is done. Right now, this does not make any big
difference, but doing so in preparation for the next patch which adds
a call to the driver.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230616094948.61701884ff0d.I3358228209eb6766202aff04d1bae0b8fdff611f@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 19e7014..8984f74 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1701,10 +1701,10 @@ cfg80211_update_known_bss(struct cfg80211_registered_device *rdev,
 }
 
 /* Returned bss is reference counted and must be cleaned up appropriately. */
-struct cfg80211_internal_bss *
-cfg80211_bss_update(struct cfg80211_registered_device *rdev,
-                   struct cfg80211_internal_bss *tmp,
-                   bool signal_valid, unsigned long ts)
+static struct cfg80211_internal_bss *
+__cfg80211_bss_update(struct cfg80211_registered_device *rdev,
+                     struct cfg80211_internal_bss *tmp,
+                     bool signal_valid, unsigned long ts)
 {
        struct cfg80211_internal_bss *found = NULL;
 
@@ -1713,10 +1713,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 
        tmp->ts = ts;
 
-       spin_lock_bh(&rdev->bss_lock);
-
        if (WARN_ON(!rcu_access_pointer(tmp->pub.ies))) {
-               spin_unlock_bh(&rdev->bss_lock);
                return NULL;
        }
 
@@ -1724,7 +1721,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 
        if (found) {
                if (!cfg80211_update_known_bss(rdev, found, tmp, signal_valid))
-                       goto drop;
+                       return NULL;
        } else {
                struct cfg80211_internal_bss *new;
                struct cfg80211_internal_bss *hidden;
@@ -1744,7 +1741,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
                        ies = (void *)rcu_dereference(tmp->pub.proberesp_ies);
                        if (ies)
                                kfree_rcu(ies, rcu_head);
-                       goto drop;
+                       return NULL;
                }
                memcpy(new, tmp, sizeof(*new));
                new->refcount = 1;
@@ -1775,14 +1772,14 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
                         */
                        if (!cfg80211_combine_bsses(rdev, new)) {
                                bss_ref_put(rdev, new);
-                               goto drop;
+                               return NULL;
                        }
                }
 
                if (rdev->bss_entries >= bss_entries_limit &&
                    !cfg80211_bss_expire_oldest(rdev)) {
                        bss_ref_put(rdev, new);
-                       goto drop;
+                       return NULL;
                }
 
                /* This must be before the call to bss_ref_get */
@@ -1799,12 +1796,22 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 
        rdev->bss_generation++;
        bss_ref_get(rdev, found);
-       spin_unlock_bh(&rdev->bss_lock);
 
        return found;
- drop:
+}
+
+struct cfg80211_internal_bss *
+cfg80211_bss_update(struct cfg80211_registered_device *rdev,
+                   struct cfg80211_internal_bss *tmp,
+                   bool signal_valid, unsigned long ts)
+{
+       struct cfg80211_internal_bss *res;
+
+       spin_lock_bh(&rdev->bss_lock);
+       res = __cfg80211_bss_update(rdev, tmp, signal_valid, ts);
        spin_unlock_bh(&rdev->bss_lock);
-       return NULL;
+
+       return res;
 }
 
 int cfg80211_get_ies_channel_number(const u8 *ie, size_t ielen,
@@ -2015,15 +2022,15 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
        rcu_assign_pointer(tmp.pub.ies, ies);
 
        signal_valid = data->chan == channel;
-       res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid, ts);
+       spin_lock_bh(&rdev->bss_lock);
+       res = __cfg80211_bss_update(rdev, &tmp, signal_valid, ts);
        if (!res)
-               return NULL;
+               goto drop;
 
        if (non_tx_data) {
                /* this is a nontransmitting bss, we need to add it to
                 * transmitting bss' list if it is not there
                 */
-               spin_lock_bh(&rdev->bss_lock);
                if (cfg80211_add_nontrans_list(non_tx_data->tx_bss,
                                               &res->pub)) {
                        if (__cfg80211_unlink_bss(rdev, res)) {
@@ -2031,15 +2038,19 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
                                res = NULL;
                        }
                }
-               spin_unlock_bh(&rdev->bss_lock);
 
                if (!res)
-                       return NULL;
+                       goto drop;
        }
+       spin_unlock_bh(&rdev->bss_lock);
 
        trace_cfg80211_return_bss(&res->pub);
-       /* cfg80211_bss_update gives us a referenced result */
+       /* __cfg80211_bss_update gives us a referenced result */
        return &res->pub;
+
+drop:
+       spin_unlock_bh(&rdev->bss_lock);
+       return NULL;
 }
 
 static const struct element
@@ -2376,6 +2387,7 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
                                      struct ieee80211_mgmt *mgmt, size_t len,
                                      gfp_t gfp)
 {
+       struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
        struct cfg80211_internal_bss tmp = {}, *res;
        struct cfg80211_bss_ies *ies;
        struct ieee80211_channel *channel;
@@ -2485,14 +2497,20 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
        ether_addr_copy(tmp.parent_bssid, data->parent_bssid);
 
        signal_valid = data->chan == channel;
-       res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid,
-                                 jiffies);
+       spin_lock_bh(&rdev->bss_lock);
+       res = __cfg80211_bss_update(rdev, &tmp, signal_valid, jiffies);
        if (!res)
-               return NULL;
+               goto drop;
+
+       spin_unlock_bh(&rdev->bss_lock);
 
        trace_cfg80211_return_bss(&res->pub);
-       /* cfg80211_bss_update gives us a referenced result */
+       /* __cfg80211_bss_update gives us a referenced result */
        return &res->pub;
+
+drop:
+       spin_unlock_bh(&rdev->bss_lock);
+       return NULL;
 }
 
 struct cfg80211_bss *