[RFA/tracepoint] Make GDB can work with some old GDB server

[Hui Zhu <teawater at gmail dot com>]

Hi,

I got some bug report about ppa in https://lkml.org/lkml/2011/6/4/65
It is:
kgdb_breakpoint () at kernel/kgdb.c:1721
1721            wmb(); /* Sync point after breakpoint */
Sending packet: $qSymbol::#5b...Ack
Packet received:
Packet qSymbol (symbol-lookup) is NOT supported
Sending packet: $qTStatus#49...Ack
Packet received: E22
trace API error 0x2.
(gdb) bt
No stack.
(gdb)

This is because this kgdb(I think trunk have fixed this bug) don't
support qtstatus and reply -0x22.
So gdb throw a error.  Then all connect process stop.

This is a bug of kgdb, but I think make gdb just output a warning is
not affect anything else.  So I make this patch.

Please help me review it.

Thanks,
Hui


2011-06-24  Hui Zhu  <teawater@gmail.com>

	* remote.c (remote_start_remote): Add TRY_CATCH for
	remote_get_trace_status.
	* tracepoint.c (disconnect_tracing): Ditto.
---
 remote.c     |   13 ++++++++++++-
 tracepoint.c |   14 +++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

--- a/remote.c
+++ b/remote.c
@@ -3146,6 +3146,8 @@ remote_start_remote (int from_tty, struc
   struct remote_state *rs = get_remote_state ();
   struct packet_config *noack_config;
   char *wait_status = NULL;
+  int ret = 0;
+  volatile struct gdb_exception ex;

   immediate_quit++;		/* Allow user to interrupt it.  */

@@ -3389,7 +3391,16 @@ remote_start_remote (int from_tty, struc

   /* Possibly the target has been engaged in a trace run started
      previously; find out where things are at.  */
-  if (remote_get_trace_status (current_trace_status ()) != -1)
+  TRY_CATCH (ex, RETURN_MASK_ERROR)
+    {
+      ret = remote_get_trace_status (current_trace_status ());
+    }
+  if (ex.reason < 0)
+    {
+      warning(_("%s"), ex.message);
+      ret = -1;
+    }
+  if (ret != -1)
     {
       struct uploaded_tp *uploaded_tps = NULL;
       struct uploaded_tsv *uploaded_tsvs = NULL;
--- a/tracepoint.c
+++ b/tracepoint.c
@@ -1939,11 +1939,23 @@ trace_status_mi (int on_stop)
 void
 disconnect_tracing (int from_tty)
 {
+  int ret = 0;
+  volatile struct gdb_exception ex;
+
   /* It can happen that the target that was tracing went away on its
      own, and we didn't notice.  Get a status update, and if the
      current target doesn't even do tracing, then assume it's not
      running anymore.  */
-  if (target_get_trace_status (current_trace_status ()) < 0)
+  TRY_CATCH (ex, RETURN_MASK_ERROR)
+    {
+      ret = target_get_trace_status (current_trace_status ());
+    }
+  if (ex.reason < 0)
+    {
+      warning(_("%s"), ex.message);
+      ret = -1;
+    }
+  if (ret < 0)
     current_trace_status ()->running = 0;

   /* If running interactively, give the user the option to cancel and