Re: [PATCH 2/2] Replace address and aspace with thread in struct step_over_info

Doug Evans
2016-04-20T18:01:21Z

Yao Qi <qiyaoltc@gmail.com> writes:
> Pedro Alves <palves@redhat.com> writes:
>
>> I think this is problematic.
>>
>> While a thread is being stepped past a breakpoint, it's possible that the
>> user sets some other breakpoint, and then we end up in
>> stepping_past_instruction_at
>> deciding whether we can insert that new breakpoint, while the step-over thread
>> is running.
>>
>> As soon as the step-over thread is resumed for the actual step-over, it's
>> regcache is flushed (target_resume -> registers_changed_ptid). From that point
>> and until the thread stops again, trying to fetch its regcache will error out,
>> because you can't read registers from a thread that is running.
>
> OK, that is a good case. I didn't think of it. I withdraw the patch.

A good place for a comment explaining Why Things Are The Way They Are.

Not sure how you want to word this.

2016-04-20 Doug Evans <xdje42@gmail.com>

* infrun.c (set_step_over_info): Add comment.

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 696105d..c7ea5e2 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1325,7 +1325,9 @@ struct step_over_info
static struct step_over_info step_over_info;

/* Record the address of the breakpoint/instruction we're currently
- stepping over. */
+ stepping over.
+ N.B. We record the aspace and address now, instead of say just the thread,
+ because when we need the info later the thread may be running. */

static void
set_step_over_info (struct address_space *aspace, CORE_ADDR address,