wifi: mac80211: Fix sparse warning for monitor_sdata

JIRA: https://issues.redhat.com/browse/RHEL-79791

commit 861d044
Author: Alexander Wetzel <Alexander@wetzel-home.de>
Date:   Thu Feb 13 22:43:30 2025 +0100

    wifi: mac80211: Fix sparse warning for monitor_sdata
    
    Use rcu_access_pointer() to avoid sparse warning in
    drv_remove_interface().
    
    Signed-off-by: Alexander Wetzel <Alexander@wetzel-home.de>
    Reported-by: kernel test robot <lkp@intel.com>
    Closes: https://lore.kernel.org/oe-kbuild-all/202502130534.bVrZZBK0-lkp@intel.com/
    Fixes: 646262c ("wifi: mac80211: remove debugfs dir for virtual monitor")
    Link: https://patch.msgid.link/20250213214330.6113-1-Alexander@wetzel-home.de
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>

Author: jtornosm

net/mac80211/driver-ops.c

@@ -121,7 +121,7 @@ void drv_remove_interface(struct ieee80211_local *local,
 	 * The virtual monitor interface doesn't get a debugfs
 	 * entry, so it's exempt here.
 	 */
-	if (sdata != local->monitor_sdata)
+	if (sdata != rcu_access_pointer(local->monitor_sdata))
 		ieee80211_debugfs_recreate_netdev(sdata,
 						  sdata->vif.valid_links);