The workqueue provided by mac80211 should not be used for
scheduled tasks that acquire the RTNL lock. This could be done
when the driver uses the function ieee80211_iterate_active_interfaces()
within the scheduled work. Such behavior will end in locking
dependencies problems when an interface is being removed.
This patch will add a notification about the RTNL locking and
the mac80211 workqueue to prevent driver developers from
blindly using it.
Signed-off-by: Ivo van Doorn <IvDoorn@xxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 19f1e41..02c79e6 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -738,8 +738,11 @@ enum ieee80211_hw_flags {
* @conf: &struct ieee80211_conf, device configuration, don't use.
*
* @workqueue: single threaded workqueue available for driver use,
- * allocated by mac80211 on registration and flushed on
- * unregistration.
+ * allocated by mac80211 on registration and flushed when an
+ * interface is removed.
+ * NOTICE: All work performed on this workqueue should NEVER
+ * acquire the RTNL lock (i.e. Don't use the function
+ * ieee80211_iterate_active_interfaces())
*
* @priv: pointer to private area that was allocated for driver use
* along with this structure.
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