wifi: mac80211: unify link STA removal in vif link removal

There are multiple cases where interface links are removed
and the station links need to be removed with them, e.g.
in mlme.c we have both received and transmitted multi-link
reconfiguration, doing the two things in different order,
the former deleting STA links when the vif link change may
still fail.

It's also not clear that userspace (hostapd) couldn't, at
least in theory, remove a link from an interface without
removing the station links first, or even leave stations
that aren't MLO-capable, using that link.

Unify this code into ieee80211_vif_update_links() so that
it always happens, always happens in the right order and
is transactional (i.e. failures are handled correctly.)

Link: https://patch.msgid.link/20260529102644.c352f73a4658.I7219a5d72dab2abcecea9b5c52e7eb7a50e68d9b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/link.c b/net/mac80211/link.c
index e81dd02de12e07e0733c8e6df1939012450a8f35..d0535268962c7acbf5df8889db7cb2ee2e6f01d4 100644 (file)
--- a/net/mac80211/link.c
+++ b/net/mac80211/link.c
@@ -292,6 +292,7 @@ static int ieee80211_vif_update_links(struct ieee80211_sub_if_data *sdata,
        u16 old_active = sdata->vif.active_links;
        unsigned long add = new_links & ~old_links;
        unsigned long rem = old_links & ~new_links;
+       unsigned long sta_rem = rem;
        unsigned int link_id;
        int ret;
        struct link_container *links[IEEE80211_MLD_MAX_NUM_LINKS] = {}, *link;
@@ -299,6 +300,7 @@ static int ieee80211_vif_update_links(struct ieee80211_sub_if_data *sdata,
        struct ieee80211_link_data *old_data[IEEE80211_MLD_MAX_NUM_LINKS];
        bool use_deflink = old_links == 0; /* set for error case */
        bool non_sta = sdata->vif.type != NL80211_IFTYPE_STATION;
+       struct sta_info *sta;
 
        lockdep_assert_wiphy(sdata->local->hw.wiphy);
 
@@ -402,6 +404,34 @@ static int ieee80211_vif_update_links(struct ieee80211_sub_if_data *sdata,
                goto free;
        }
 
+       /* try to remove links that are now invalid from (MLO) stations */
+       list_for_each_entry(sta, &sdata->local->sta_list, list) {
+               unsigned long rem_links = sta->sta.valid_links & sta_rem;
+
+               if (sta->sdata != sdata)
+                       continue;
+
+               /*
+                * skip stations that would have no links left,
+                * those will be removed completely later
+                */
+               if (sta->sta.valid_links == rem_links)
+                       continue;
+
+               for_each_set_bit(link_id, &rem_links,
+                                IEEE80211_MLD_MAX_NUM_LINKS)
+                       ieee80211_sta_remove_link(sta, link_id);
+       }
+
+       /*
+        * Remove stations using any removed links. Note that due
+        * to the above station link removal, this only removes
+        * stations that were skipped above because they'd have no
+        * links left after link removal.
+        */
+       for_each_set_bit(link_id, &sta_rem, IEEE80211_MLD_MAX_NUM_LINKS)
+               sta_info_flush(sdata, link_id);
+
        /* use deflink/bss_conf again if and only if there are no more links */
        use_deflink = new_links == 0;
 

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index cfb5bc4eac69ab0cbf8dafb7be2c44410ddb900c..f55cb376cbd517b24ecd95a8cfd09b2c9151d760 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -7169,7 +7169,6 @@ static void ieee80211_ml_reconf_work(struct wiphy *wiphy,
                container_of(work, struct ieee80211_sub_if_data,
                             u.mgd.ml_reconf_work.work);
        u16 new_valid_links, new_active_links, new_dormant_links;
-       struct sta_info *sta;
        int ret;
 
        if (!sdata->u.mgd.removed_links)
@@ -7205,16 +7204,6 @@ static void ieee80211_ml_reconf_work(struct wiphy *wiphy,
                }
        }
 
-       sta = sta_info_get(sdata, sdata->vif.cfg.ap_addr);
-       if (sta) {
-               unsigned long removed_links = sdata->u.mgd.removed_links;
-               unsigned int link_id;
-
-               for_each_set_bit(link_id, &removed_links,
-                                IEEE80211_MLD_MAX_NUM_LINKS)
-                       ieee80211_sta_remove_link(sta, link_id);
-       }
-
        new_dormant_links = sdata->vif.dormant_links & ~sdata->u.mgd.removed_links;
 
        ret = ieee80211_vif_set_links(sdata, new_valid_links,
@@ -11071,14 +11060,6 @@ int ieee80211_mgd_assoc_ml_reconf(struct ieee80211_sub_if_data *sdata,
                        goto err_free;
                }
 
-               for (link_id = 0; link_id < IEEE80211_MLD_MAX_NUM_LINKS;
-                    link_id++) {
-                       if (!(req->rem_links & BIT(link_id)))
-                               continue;
-
-                       ieee80211_sta_remove_link(sta, link_id);
-               }
-
                /* notify the driver and upper layers */
                ieee80211_vif_cfg_change_notify(sdata,
                                                BSS_CHANGED_MLD_VALID_LINKS);