[patch] Fix for PR gdb/10838

[ppluzhnikov at google dot com (Paul Pluzhnikov)]

Greetings,

In http://sourceware.org/bugzilla/show_bug.cgi?id=10838
gdb attach; detach; attach sequence leaves libpthread in hosed state.

The root cause turned out to be that this:

      td_event_emptyset (&events);
      info->td_ta_set_event_p (info->thread_agent, &events);

is a no-op -- glibc ORs new event bits in, but doesn't clear any already
set bits. To clear them, one must call td_ta_clear_event() instead.

Here is a patch which fixes this in gdb and gdbserver.

Tested (GDB only) on Linux/x86_64 with no regressions.

Thanks,
--
Paul Pluzhnikov

gdb/ChangeLog:

2009-11-11  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/10838
	* linux-thread-db.c (thread_db_info): New member.
	(disable_thread_event_reporting): Call td_ta_clear_event.

gdbserver/ChangeLog:

2009-11-11  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/10838
	* thread-db.c (thread_db_free): Call td_ta_clear_event.

Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.67
diff -u -p -u -r1.67 linux-thread-db.c
--- linux-thread-db.c	3 Nov 2009 17:14:56 -0000	1.67
+++ linux-thread-db.c	12 Nov 2009 00:21:02 -0000
@@ -141,6 +141,8 @@ struct thread_db_info
 				  td_event_e event, td_notify_t *ptr);
   td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
 				 td_thr_events_t *event);
+  td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
+				   td_thr_events_t *event);
   td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
 				    td_event_msg_t *msg);
 
@@ -701,6 +703,7 @@ try_thread_db_load_1 (struct thread_db_i
   /* These are not essential.  */
   info->td_ta_event_addr_p = dlsym (info->handle, "td_ta_event_addr");
   info->td_ta_set_event_p = dlsym (info->handle, "td_ta_set_event");
+  info->td_ta_clear_event_p = dlsym (info->handle, "td_ta_clear_event");
   info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
   info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
   info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
@@ -907,14 +910,14 @@ thread_db_load (void)
 static void
 disable_thread_event_reporting (struct thread_db_info *info)
 {
-  if (info->td_ta_set_event_p != NULL)
+  if (info->td_ta_clear_event_p != NULL)
     {
       td_thr_events_t events;
 
       /* Set the process wide mask saying we aren't interested in any
 	 events anymore.  */
-      td_event_emptyset (&events);
-      info->td_ta_set_event_p (info->thread_agent, &events);
+      td_event_fillset (&events);
+      info->td_ta_clear_event_p (info->thread_agent, &events);
     }
 
   info->td_create_bp_addr = 0;
Index: gdbserver/thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/thread-db.c,v
retrieving revision 1.26
diff -u -p -u -r1.26 thread-db.c
--- gdbserver/thread-db.c	29 Oct 2009 17:43:44 -0000	1.26
+++ gdbserver/thread-db.c	12 Nov 2009 00:21:02 -0000
@@ -759,6 +759,19 @@ thread_db_free (struct process_info *pro
     {
 #ifndef USE_LIBTHREAD_DB_DIRECTLY
       td_err_e (*td_ta_delete_p) (td_thragent_t *);
+      td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
+				       td_thr_events_t *event);
+
+      td_ta_clear_event_p = dlsym (thread_db->handle, "td_ta_clear_event");
+      if (td_ta_clear_event_p != NULL)
+	{
+	  td_thr_events_t events;
+
+	  /* Set the process wide mask saying we aren't interested in any
+	     events anymore.  */
+	  td_event_fillset (&events);
+	  (*td_ta_clear_event_p) (thread_db->thread_agent, &events);
+	}
 
       td_ta_delete_p = dlsym (thread_db->handle, "td_ta_delete");
       if (td_ta_delete_p != NULL)
@@ -766,6 +779,10 @@ thread_db_free (struct process_info *pro
 
       dlclose (thread_db->handle);
 #else
+      td_thd_events_t events;
+
+      td_event_fillset (&events);
+      td_ta_clear_event (thread_db->thread_agent, &events);
       td_ta_delete (thread_db->thread_agent);
 #endif  /* USE_LIBTHREAD_DB_DIRECTLY  */