Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.16
diff -u -p -r1.16 linux-thread-db.c
--- linux-thread-db.c	5 May 2006 22:42:43 -0000	1.16
+++ linux-thread-db.c	20 Jun 2006 17:51:01 -0000
@@ -1006,6 +1006,9 @@ thread_db_fetch_registers (int regno)
     }
 
   thread_info = find_thread_pid (inferior_ptid);
+  if (!thread_info)
+    error (_("Stopped at dead thread %ld; should not happen."),
+	   (long) GET_THREAD (inferior_ptid));
   thread_db_map_id2thr (thread_info, 1);
 
   err = td_thr_getgregs_p (&thread_info->private->th, gregset);
@@ -1127,6 +1130,8 @@ thread_db_thread_alive (ptid_t ptid)
       struct thread_info *thread_info;
       thread_info = find_thread_pid (ptid);
 
+      if (!thread_info)
+	return 0;
       thread_db_map_id2thr (thread_info, 0);
       if (!thread_info->private->th_valid)
 	return 0;
@@ -1145,9 +1150,9 @@ thread_db_thread_alive (ptid_t ptid)
 	  thread_info->private->ti_valid = 1;
 	}
 
-      if (thread_info->private->ti.ti_state == TD_THR_UNKNOWN
-	  || thread_info->private->ti.ti_state == TD_THR_ZOMBIE)
-	return 0;		/* A zombie thread.  */
+      /* Never 0 on TD_THR_ZOMBIE to be able to trace pthread_exit(3).  */
+      if (thread_info->private->ti.ti_state == TD_THR_UNKNOWN)
+	return 0;		/* A disappeared thread.  */
 
       return 1;
     }