Fix error when gdb connect to a stub that tracepoint is running[1/2] Add a flag initialized to struct trace_status

[Hui Zhu <hui_zhu@mentor.com>]

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Hi Pedro,

After discussion with Yao in irc, our thought is if we want handle it in 
update_global_location_list, there will a lot of part need to be change, 
because there are a lot of call level.  For example:
#0  remote_download_tracepoint (loc=0x35040b0) at 
../../src/gdb/remote.c:9982
#1  0x00000000006727c1 in download_tracepoint_locations () at 
../../src/gdb/breakpoint.c:10670
#2  0x0000000000673111 in update_global_location_list (should_insert=1) 
at ../../src/gdb/breakpoint.c:11021
#3  0x0000000000663752 in create_overlay_event_breakpoint () at 
../../src/gdb/breakpoint.c:2322
#4  0x0000000000675c9f in breakpoint_re_set () at 
../../src/gdb/breakpoint.c:12621
#5  0x00000000007efe65 in solib_add (pattern=0x0, from_tty=1, 
target=0x1d1e860, readsyms=1)
      at ../../src/gdb/solib.c:928
#6  0x000000000057b452 in enable_break (info=0x3307890, from_tty=1) at 
../../src/gdb/solib-svr4.c:1624
#7  0x000000000057c428 in svr4_solib_create_inferior_hook (from_tty=1) 
at ../../src/gdb/solib-svr4.c:2234
#8  0x00000000007f04a9 in solib_create_inferior_hook (from_tty=1) at 
../../src/gdb/solib.c:1172
#9  0x00000000006cc8e5 in post_create_inferior (target=0x1d1e860, 
from_tty=1) at ../../src/gdb/infcmd.c:431
#10 0x00000000006d479d in start_remote (from_tty=1) at 
../../src/gdb/infrun.c:2309
#11 0x00000000005d80c9 in remote_start_remote (from_tty=1, 
target=0x1cefce0, extended_p=0)
      at ../../src/gdb/remote.c:3367

The idea of this patch is let remote_get_trace_status doesn't try to 
access to target status before remote_start_remote call 
remote_get_trace_status.  Then when GDB call 
download_tracepoint_locations try to download tracepoint before call 
remote_get_trace_status, it will got !ts->running_known in 
remote_can_download_tracepoint.  Then GDB will not download tracepoint 
before remote_start_remote call remote_get_trace_status.

BTW, to handle this issue we need patch in
http://sourceware.org/ml/gdb-patches/2012-01/msg01008.html too.

Thanks,
Hui

2012-02-27  Hui Zhu  <hui_zhu@mentor.com>
	    Yao Qi  <yao@codesourcery.com>

	* remote.c (remote_start_remote): ts->initialized to false in the
	begin of this function and set it to true before
	call remote_get_trace_status.
	(remote_get_trace_status): Return directly if ts->initialized is false.
	tracepoint.c(tfile_open): Set ts->initialized to true.
	tracepoint.h(trace_status): Add initialized.



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---
 remote.c     |   30 ++++++++++++++++++++----------
 tracepoint.c |    1 +
 tracepoint.h |    3 +++
 3 files changed, 24 insertions(+), 10 deletions(-)

--- a/remote.c
+++ b/remote.c
@@ -3203,6 +3203,7 @@ remote_start_remote (int from_tty, struc
   struct remote_state *rs = get_remote_state ();
   struct packet_config *noack_config;
   char *wait_status = NULL;
+  struct trace_status *ts = current_trace_status ();
 
   immediate_quit++;		/* Allow user to interrupt it.  */
 
@@ -3212,6 +3213,9 @@ remote_start_remote (int from_tty, struc
   /* Ack any packet which the remote side has already sent.  */
   serial_write (remote_desc, "+", 1);
 
+  /* Set status to not initialized.  */
+  ts->initialized = 0;
+
   /* The first packet we send to the target is the optional "supported
      packets" request.  If the target can answer this, it will tell us
      which later probes to skip.  */
@@ -3435,7 +3439,8 @@ 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)
+  ts->initialized = 1;
+  if (remote_get_trace_status (ts) != -1)
     {
       struct uploaded_tp *uploaded_tps = NULL;
       struct uploaded_tsv *uploaded_tsvs = NULL;
@@ -10276,6 +10281,19 @@ remote_get_trace_status (struct trace_st
   extern int trace_regblock_size;
   volatile struct gdb_exception ex;
 
+  /* We're working with a live target.  */
+  ts->from_file = 0;
+
+  /* Set some defaults.  */
+  ts->running_known = 0;
+  ts->stop_reason = trace_stop_reason_unknown;
+  ts->traceframe_count = -1;
+  ts->buffer_free = 0;
+  ts->running = 0;
+
+  if (!ts->initialized)
+    goto out;
+
   trace_regblock_size = get_remote_arch_state ()->sizeof_g_packet;
 
   putpkt ("qTStatus");
@@ -10294,20 +10312,12 @@ remote_get_trace_status (struct trace_st
   if (*p == '\0')
     return -1;
 
-  /* We're working with a live target.  */
-  ts->from_file = 0;
-
-  /* Set some defaults.  */
-  ts->running_known = 0;
-  ts->stop_reason = trace_stop_reason_unknown;
-  ts->traceframe_count = -1;
-  ts->buffer_free = 0;
-
   if (*p++ != 'T')
     error (_("Bogus trace status reply from target: %s"), target_buf);
 
   parse_trace_status (p, ts);
 
+out:
   return ts->running;
 }
 
--- a/tracepoint.c
+++ b/tracepoint.c
@@ -3670,6 +3670,7 @@ tfile_open (char *filename, int from_tty
 
   trace_regblock_size = 0;
   ts = current_trace_status ();
+  ts->initialized = 1;
   /* We know we're working with a file.  */
   ts->from_file = 1;
   /* Set defaults in case there is no status line.  */
--- a/tracepoint.h
+++ b/tracepoint.h
@@ -72,6 +72,9 @@ enum trace_stop_reason
 
 struct trace_status
 {
+  /* The target will try to get the status only when this is true.  */
+  int initialized;
+
   /* This is true if the status is coming from a file rather
      than a live target.  */
   int from_file;