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

[Pedro Alves <palves@redhat.com>]

Hi Hui, Yao.  Sorry for the delay.  I'm looking at this now.

On 03/01/2012 02:46 PM, Hui Zhu wrote:
> 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.
> 

I think this is close, but still not quite right.  This isn't fundamentally
about the remote side's trace status; so having remote_get_trace_status
return something different while going through initialization feels wrong.
Let me try tweaking this a bit.  I'll also hack a bit on patch 2/2.

> 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.


-- 
Pedro Alves