Currently, the existing macro for_each_link_data() uses sdata_dereference() which requires the wiphy lock. This lock cannot be used in atomic or RCU read-side contexts, such as in the RX path. Introduce a new macro, for_each_link_data_rcu(), that iterates over link of sdata using rcu_dereference(), making it safe to use in RCU contexts. This allows callers to access link data without requiring the wiphy lock. The macro takes into account the vif.valid_links bitmap and ensures only valid links are accessed safely. Callers are responsible for ensuring that rcu_read_lock() is held when using this macro. Signed-off-by: Maharaja Kennadyrajan <maharaja.kennadyrajan@xxxxxxxxxxxxxxxx> --- net/mac80211/ieee80211_i.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 7c18c51966d0..9c0603eb580f 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1252,6 +1252,19 @@ struct ieee80211_sub_if_data *vif_to_sdata(struct ieee80211_vif *p) ((__link) = sdata_dereference((__sdata)->link[__link_id], \ (__sdata)))) +/* + * for_each_link_data_rcu should be used under RCU read lock. + */ +#define for_each_link_data_rcu(sdata, __link) \ + /* outer loop just to define the variable ... */ \ + for (struct ieee80211_sub_if_data *__sdata = (sdata); __sdata; \ + __sdata = NULL /* always stop */) \ + for (int __link_id = 0; \ + __link_id < ARRAY_SIZE((__sdata)->link); __link_id++) \ + if ((!(__sdata)->vif.valid_links || \ + (__sdata)->vif.valid_links & BIT(__link_id)) && \ + ((__link) = rcu_dereference((__sdata)->link[__link_id]))) \ + static inline int ieee80211_get_mbssid_beacon_len(struct cfg80211_mbssid_elems *elems, struct cfg80211_rnr_elems *rnr_elems, -- 2.17.1
