mac80211: make scan_sdata pointer usable with RCU

Making the scan_sdata pointer usable with RCU makes
it possible to dereference it in the RX path to see
if a received frame actually matches the interface
that is scanning. This is just preparations, making
the pointer __rcu.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index b1edf60fbba7..e3c49748ce8f 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -112,10 +112,11 @@ static u32 __ieee80211_recalc_idle(struct ieee80211_local *local)
                 }
         }
 
-        if (local->scan_sdata &&
-            !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
+        sdata = rcu_dereference_protected(local->scan_sdata,
+                                          lockdep_is_held(&local->mtx));
+        if (sdata && !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
                 scanning = true;
-                local->scan_sdata->vif.bss_conf.idle = false;
+                sdata->vif.bss_conf.idle = false;
         }
 
         list_for_each_entry(sdata, &local->interfaces, list) {
@@ -628,7 +629,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 
         clear_bit(SDATA_STATE_RUNNING, &sdata->state);
 
-        if (local->scan_sdata == sdata)
+        if (rcu_access_pointer(local->scan_sdata) == sdata)
                 ieee80211_scan_cancel(local);
 
         /*