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wifi: mac80211: use RCU-safe iteration in ieee80211_csa_finish

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The ieee80211_csa_finish() function currently uses for_each_sdata_link()
to iterate over links of sdata. However, this macro internally uses
wiphy_dereference(), which expects the wiphy->mtx lock to be held.
When ieee80211_csa_finish() is invoked under an RCU read-side critical
section (e.g., under rcu_read_lock()), this leads to a warning from the
RCU debugging framework.

  WARNING: suspicious RCU usage
  net/mac80211/cfg.c:3830 suspicious rcu_dereference_protected() usage!

This warning is triggered because wiphy_dereference() is not safe to use
without holding the wiphy mutex, and it is being used in an RCU context
without the required locking.

Fix this by introducing and using a new macro, for_each_sdata_link_rcu(),
which performs RCU-safe iteration over sdata links using
list_for_each_entry_rcu() and rcu_dereference(). This ensures that the
link pointers are accessed safely under RCU and eliminates the warning.

Fixes: f600832794c9 ("wifi: mac80211: restructure tx profile retrieval for MLO MBSSID")
Signed-off-by: Maharaja Kennadyrajan <maharaja.kennadyrajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250711033846.40455-1-maharaja.kennadyrajan@oss.qualcomm.com
[unindent like the non-RCU macro]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Maharaja Kennadyrajan 2025-07-11 09:08:46 +05:30 committed by Johannes Berg
parent 3df924c8f7
commit 9975aeebe2
2 changed files with 16 additions and 1 deletions
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2
net/mac80211/cfg.c
View File

@ -3841,7 +3841,7 @@ void ieee80211_csa_finish(struct ieee80211_vif *vif, unsigned int link_id)
*/
struct ieee80211_link_data *iter;
for_each_sdata_link(local, iter) {
for_each_sdata_link_rcu(local, iter) {
if (iter->sdata == sdata ||
rcu_access_pointer(iter->conf->tx_bss_conf) != tx_bss_conf)
continue;

15
net/mac80211/ieee80211_i.h
View File

@ -1226,6 +1226,21 @@ struct ieee80211_sub_if_data *vif_to_sdata(struct ieee80211_vif *p)
if ((_link = wiphy_dereference((_local)->hw.wiphy, \
___sdata->link[___link_id])))
/*
* for_each_sdata_link_rcu() must be used under RCU read lock.
*/
#define for_each_sdata_link_rcu(_local, _link) \
/* outer loop just to define the variables ... */ \
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; \
___link_id < ARRAY_SIZE((___sdata)->link); \
___link_id++) \
if ((_link = rcu_dereference((___sdata)->link[___link_id])))
#define for_each_link_data(sdata, __link) \
struct ieee80211_sub_if_data *__sdata = sdata; \
for (int __link_id = 0; \