Clarify a comment that was, well, just wrong. It turns out that

ignoring the way that macros expand. Instead, I have clarified in the
comment why the macro will work even if the scheduler id for the
task to be deleted changes during the execution of the macro.



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@115196 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/sched.h

@@ -41,17 +41,11 @@ extern "C" {
  * then whatever callback had been running will complete
  * and reinsert the task into the scheduler.
  *
- * Note that this is NOT always appropriate. This should 
+ * Since macro expansion essentially works like pass-by-name
- * only be used for tasks whose callback may return non-zero 
+ * parameter passing, this macro will still work correctly even
- * to indicate that the task needs to be rescheduled with the
+ * if the id of the task to delete changes. This holds as long as 
- * SAME id as previously.
+ * the name of the id which could change is passed to the macro 
- *
+ * and not a copy of the value of the id.
- * Some scheduler callbacks instead may reschedule the task themselves,
- * thus removing the previous task id from the queue. If the task is rescheduled
- * in this manner, then the id for the task will be different than before
- * and so it makes no sense to use this macro. Note that if using the scheduler
- * in this manner, it is perfectly acceptable for ast_sched_del to fail, and this
- * macro should NOT be used.
  */
 #define AST_SCHED_DEL(sched, id) \
 	({ \