wifi: mac80211: make link iteration safe for 'break'

The current link iteration macros for_each_sdata_link() and
for_each_sdata_link_rcu() are various nested for loops, but
because they iterate all sdata instances and then all links
inside, using 'break' inside the iteration doesn't actually
break out of the whole iteration.

Make it work by tracking whether or not the inner iteration
(over links) actually completed, if it broke out then given
list_for_each_entry() it still iterates all sdata instances
but won't go into them.

Link: https://patch.msgid.link/20251105160431.c21956654fc0.I8d4739af061c44c57d172f19a15303a44ad1e596@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 878c3b14aeb806f6d7088d97abcd4e49cbaabe6e..72e4f326946fa85d510d0a8206426aeb0f8ccb2d 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1239,9 +1239,12 @@ struct ieee80211_sub_if_data *vif_to_sdata(struct ieee80211_vif *p)
        for (struct ieee80211_sub_if_data *___sdata = NULL;             \
             !___sdata;                                                 \
             ___sdata = (void *)~0 /* always stop */)                   \
+       for (int ___link_id = ARRAY_SIZE(___sdata->link);               \
+            ___link_id; ___link_id = 0 /* always stop */)              \
        list_for_each_entry(___sdata, &(_local)->interfaces, list)      \
-       if (ieee80211_sdata_running(___sdata))                          \
-       for (int ___link_id = 0;                                        \
+       if (___link_id == ARRAY_SIZE(___sdata->link) &&                 \
+           ieee80211_sdata_running(___sdata))                          \
+       for (___link_id = 0;                                            \
             ___link_id < ARRAY_SIZE(___sdata->link);                   \
             ___link_id++)                                              \
        if ((_link = wiphy_dereference((_local)->hw.wiphy,              \
@@ -1255,9 +1258,12 @@ struct ieee80211_sub_if_data *vif_to_sdata(struct ieee80211_vif *p)
        for (struct ieee80211_sub_if_data *___sdata = NULL;                             \
             !___sdata;                                                                 \
             ___sdata = (void *)~0 /* always stop */)                                   \
-       list_for_each_entry_rcu(___sdata, &(_local)->interfaces, list)                  \
-       if (ieee80211_sdata_running(___sdata))                                          \
-       for (int ___link_id = 0;                                                        \
+       for (int ___link_id = ARRAY_SIZE(___sdata->link);               \
+            ___link_id; ___link_id = 0 /* always stop */)              \
+       list_for_each_entry(___sdata, &(_local)->interfaces, list)      \
+       if (___link_id == ARRAY_SIZE(___sdata->link) &&                 \
+           ieee80211_sdata_running(___sdata))                          \
+       for (___link_id = 0;                                            \
             ___link_id < ARRAY_SIZE((___sdata)->link);                                 \
             ___link_id++)                                                              \
        if ((_link = rcu_dereference((___sdata)->link[___link_id])))