From: Pedro Alves <pedro@codesourcery.com>
To: gdb-patches@sourceware.org
Cc: Phil Muldoon <pmuldoon@redhat.com>, tromey@redhat.com
Subject: Re: [python][patch] Inferior and Thread information support.
Date: Tue, 15 Jun 2010 15:24:00 -0000 [thread overview]
Message-ID: <201006151623.55766.pedro@codesourcery.com> (raw)
In-Reply-To: <4C1623C1.6090205@redhat.com>
On Monday 14 June 2010 13:42:41, Phil Muldoon wrote:
> On 06/10/2010 07:40 PM, Tom Tromey wrote:
> >>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:
> >
> > Phil> + THPY_REQUIRE_VALID (thread_obj);
> > Phil> +
> > Phil> + cleanup = make_cleanup_restore_current_thread ();
> > Phil> +
> > Phil> + TRY_CATCH (except, RETURN_MASK_ALL)
> > Phil> + {
> > Phil> + switch_to_thread (thread_obj->thread->ptid);
> > Phil> +
> > Phil> + frame = get_current_frame ();
> > Phil> + frame_obj = frame_info_to_frame_object (frame);
> > Phil> + }
> > Phil> + GDB_PY_HANDLE_EXCEPTION (except);
> >
> > I am really not sure about this.
> >
> > Doesn't switch_to_thread reset the frame cache?
> > Meaning that the returned frame_obj will immediately be invalid?
> >
> > You would have to try this with a multi-threaded program, where you are
> > stopped in thread A but then request a frame in thread B.
>
> I'll investigate this further. I had concerns about this (I think we
> chatted a little about this on irc way back when). I'll write an
> inferior test and see. Maybe Pedro or someone else in that area knows
> a little more.
Tom is correct. You'll not see a problem with single-thread apps
because switch_to_thread does an early return before invalidating
the frame cache when the thread you're switching to is already current.
In short, don't ever store a frame_info pointer like this. Instead,
if you need to record the frame somewhere, store a frame_id.
(I haven't really looked at the patch and the use case, just
commenting from the what's quoted above)
--
Pedro Alves
next prev parent reply other threads:[~2010-06-15 15:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-24 13:36 Phil Muldoon
2010-05-24 18:06 ` Eli Zaretskii
2010-06-10 18:40 ` Tom Tromey
2010-06-14 12:42 ` Phil Muldoon
2010-06-15 15:24 ` Pedro Alves [this message]
2010-06-15 18:11 ` Tom Tromey
2010-06-15 18:24 ` Pedro Alves
2010-06-15 19:58 ` Phil Muldoon
2010-06-15 20:36 ` Pedro Alves
2010-06-18 6:49 ` Phil Muldoon
2010-06-18 14:21 ` Doug Evans
2010-06-18 15:47 ` Phil Muldoon
2010-06-18 17:59 ` Tom Tromey
2010-06-18 20:10 ` Phil Muldoon
2010-06-25 20:41 ` Tom Tromey
2010-06-18 18:04 ` Tom Tromey
2010-06-22 10:32 ` Phil Muldoon
2010-06-25 20:38 ` Tom Tromey
2010-06-28 9:22 ` Phil Muldoon
2010-06-28 19:51 ` Tom Tromey
2010-06-28 21:35 ` Phil Muldoon
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