From: Doug Evans <xdje42@gmail.com>
To: Yao Qi <qiyaoltc@gmail.com>, Pedro Alves <palves@redhat.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH 2/2] Replace address and aspace with thread in struct step_over_info
Date: Wed, 20 Apr 2016 18:01:00 -0000 [thread overview]
Message-ID: <m34mawrwgl.fsf@sspiff.org> (raw)
In-Reply-To: <86a8kpk8k1.fsf@gmail.com> (Yao Qi's message of "Tue, 19 Apr 2016 14:54:54 +0100")
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,
next prev parent reply other threads:[~2016-04-20 18:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-15 13:29 [PATCH 0/2] Add thread info in 'struct step_over_info' Yao Qi
2016-04-15 13:29 ` [PATCH 2/2] Replace address and aspace with thread in struct step_over_info Yao Qi
2016-04-19 10:43 ` Pedro Alves
2016-04-19 13:55 ` Yao Qi
2016-04-20 18:01 ` Doug Evans [this message]
2016-04-20 18:03 ` Pedro Alves
2016-12-22 23:51 ` Doug Evans
2016-04-15 13:29 ` [PATCH 1/2] Refactor function set_step_over_info Yao Qi
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