Added some missing locks when calling functions from cStatus or cSkin*

1 files changed, 12 insertions, 1 deletions

diff --git a/skins.h b/skins.h
index 2286087b..f994d47d 100644
--- a/skins.h
+++ b/skins.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: skins.h 4.1 2015/09/10 11:19:48 kls Exp $
+ * $Id: skins.h 4.2 2017/06/21 09:40:39 kls Exp $
  */
 
 #ifndef __SKINS_H
@@ -21,6 +21,17 @@
 #include "timers.h"
 #include "tools.h"
 
+// Several member functions of the following classes are called with a pointer to
+// an object from a global list (cTimer, cChannel, cRecording or cEvent). In these
+// cases the core VDR code holds a lock on the respective list. The called function
+// may itself set a read lock (not a write lock!) on this list, because read locks
+// can be nested. It may also set read locks (not write locks!) on higher order lists.
+// For instance, a function that is called with a cChannel may lock cRecordings and/or
+// cSchedules (which contains cEvent objects), but not cTimers. If a plugin needs to
+// set locks of its own (on mutexes defined inside the plugin code), it shall do so
+// after setting any locks on VDR's global lists, and it shall always set these
+// locks in the same sequence, to avoid deadlocks.
+
 enum eMessageType { mtStatus = 0, mtInfo, mtWarning, mtError }; // will be used to calculate color offsets!
 
 class cSkinDisplay {