mac80211: fix debugfs lockup

When debugfs_create_dir fails, sta_info_debugfs_add_work will not
terminate because it will find the same station again and again.
This is possible whenever debugfs fails for whatever reason; one
reason is a race condition in mac80211, unfortunately we cannot
do much about it, so just document it, it just means some station
may be missing from debugfs.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 9b72d15bc8dc..7fef8ea1f5ec 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -635,7 +635,12 @@ static void sta_info_debugfs_add_work(struct work_struct *work)
 
                 spin_lock_irqsave(&local->sta_lock, flags);
                 list_for_each_entry(tmp, &local->sta_list, list) {
-                        if (!tmp->debugfs.dir) {
+                        /*
+                         * debugfs.add_has_run will be set by
+                         * ieee80211_sta_debugfs_add regardless
+                         * of what else it does.
+                         */
+                        if (!tmp->debugfs.add_has_run) {
                                 sta = tmp;
                                 __sta_info_pin(sta);
                                 break;