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wifi: mac80211: Add link iteration macro for link data with rcu_dereference

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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@oss.qualcomm.com>
Link: https://patch.msgid.link/20250718060837.59371-3-maharaja.kennadyrajan@oss.qualcomm.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Maharaja Kennadyrajan 2025-07-18 11:38:35 +05:30 committed by Johannes Berg
parent f562f6a589
commit 4e1916dec9
1 changed files with 13 additions and 0 deletions
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13
net/mac80211/ieee80211_i.h
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@ -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,