diff options
| author | Johannes Berg <johannes@sipsolutions.net> | 2008-10-07 12:04:29 +0200 |
|---|---|---|
| committer | John W. Linville <linville@tuxdriver.com> | 2008-10-15 02:46:41 +0200 |
| commit | 63044e9f54b6bac50d2380bf4d14f63e9e7de72b (patch) | |
| tree | 9ceddf721c869fb9450429fd4932d8c40b765486 /net/mac80211 | |
| parent | iwlwifi: fix compilation warning when CONFIG_IWLWIFI_DEBUG is not set. (diff) | |
| download | linux-63044e9f54b6bac50d2380bf4d14f63e9e7de72b.tar.xz linux-63044e9f54b6bac50d2380bf4d14f63e9e7de72b.zip | |
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>
Diffstat (limited to 'net/mac80211')
| -rw-r--r-- | net/mac80211/debugfs_sta.c | 11 | ||||
| -rw-r--r-- | net/mac80211/sta_info.c | 7 | ||||
| -rw-r--r-- | net/mac80211/sta_info.h | 1 |
3 files changed, 18 insertions, 1 deletions
diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c index b9902e425f09..189d0bafa91a 100644 --- a/net/mac80211/debugfs_sta.c +++ b/net/mac80211/debugfs_sta.c @@ -249,11 +249,22 @@ void ieee80211_sta_debugfs_add(struct sta_info *sta) DECLARE_MAC_BUF(mbuf); u8 *mac; + sta->debugfs.add_has_run = true; + if (!stations_dir) return; mac = print_mac(mbuf, sta->sta.addr); + /* + * This might fail due to a race condition: + * When mac80211 unlinks a station, the debugfs entries + * remain, but it is already possible to link a new + * station with the same address which triggers adding + * it to debugfs; therefore, if the old station isn't + * destroyed quickly enough the old station's debugfs + * dir might still be around. + */ sta->debugfs.dir = debugfs_create_dir(mac, stations_dir); if (!sta->debugfs.dir) return; 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; diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h index a6b51862a89d..168a39a298bd 100644 --- a/net/mac80211/sta_info.h +++ b/net/mac80211/sta_info.h @@ -300,6 +300,7 @@ struct sta_info { struct dentry *inactive_ms; struct dentry *last_seq_ctrl; struct dentry *agg_status; + bool add_has_run; } debugfs; #endif |