From: Daniel Colascione <dancol@dancol.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: eggert@cs.ucla.edu, emacs-devel@gnu.org
Subject: Re: Conservative GC isn't safe
Date: Sat, 26 Nov 2016 01:04:18 -0800 [thread overview]
Message-ID: <dca090ba-1eea-8c4f-1b1c-6edd97915666@dancol.org> (raw)
In-Reply-To: <8360na399k.fsf@gnu.org>
On 11/26/2016 01:01 AM, Eli Zaretskii wrote:
>> From: Daniel Colascione <dancol@dancol.org>
>> Date: Sat, 26 Nov 2016 00:33:13 -0800
>>
>>>> 2) INTERVAL is GCed, but it's not represented in the memory tree:
>>>> struct interval isn't a real lisp object and it's allocated as
>>>> MEM_TYPE_NON_LISP. Even a direct pointer to the start of an interval
>>>> won't protect it from GC. Shouldn't we treat intervals like conses?
>>>
>>> Does the code ever create an interval that is accessible only via locals
>>> when a GC occurs? If not, Emacs should be OK. (This should also be
>>> documented better.)
>>
>> Anywhere in the code? Forever? I wouldn't be confident saying so.
>
> A simple practical solution to such assumptions is to add an assertion
> in some strategic place(s).
>
> I don't think it's TRT to sprinkle our sources with code that is there
> "just in case", i.e. it will never actually run.
How would you assert dynamically that if an interval is reachable, its
owning string or buffer must be too? It's not enough for the variable
holding the reference to the string or buffer to be in scope: you have
to be sure that the reference isn't dead.
next prev parent reply other threads:[~2016-11-26 9:04 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-26 8:11 Conservative GC isn't safe Daniel Colascione
2016-11-26 8:30 ` Paul Eggert
2016-11-26 8:33 ` Daniel Colascione
2016-11-26 9:01 ` Eli Zaretskii
2016-11-26 9:04 ` Daniel Colascione [this message]
2016-11-26 9:24 ` Eli Zaretskii
2016-11-26 15:05 ` Stefan Monnier
2016-11-26 15:21 ` Camm Maguire
2016-11-28 17:51 ` Daniel Colascione
2016-11-28 18:00 ` Eli Zaretskii
2016-11-28 18:03 ` Daniel Colascione
2016-11-28 18:50 ` Eli Zaretskii
2016-11-28 18:03 ` Stefan Monnier
2016-11-28 19:18 ` Daniel Colascione
2016-11-28 19:33 ` Stefan Monnier
2016-11-28 19:37 ` Eli Zaretskii
2016-11-28 19:40 ` Daniel Colascione
2016-11-28 20:03 ` Eli Zaretskii
2016-11-28 20:09 ` Daniel Colascione
2016-11-28 19:26 ` Andreas Schwab
2016-11-28 19:34 ` Stefan Monnier
2016-11-26 15:03 ` Stefan Monnier
2016-11-26 15:12 ` Eli Zaretskii
2016-11-26 16:29 ` Stefan Monnier
2016-11-26 16:42 ` Eli Zaretskii
2016-11-26 18:43 ` Stefan Monnier
2016-11-27 6:17 ` Ken Raeburn
2016-11-27 15:39 ` Eli Zaretskii
2016-11-28 9:50 ` Ken Raeburn
2016-11-28 15:55 ` Eli Zaretskii
2016-11-27 16:15 ` Paul Eggert
2016-11-28 9:36 ` Ken Raeburn
2016-11-28 15:55 ` Eli Zaretskii
2016-11-28 16:15 ` Stefan Monnier
2016-11-28 17:37 ` Eli Zaretskii
2016-11-28 17:49 ` Stefan Monnier
2016-11-28 17:57 ` Eli Zaretskii
2016-11-28 18:05 ` Stefan Monnier
2016-11-28 19:09 ` Ken Raeburn
2016-11-28 19:33 ` Eli Zaretskii
2016-11-29 8:49 ` Ken Raeburn
2016-11-28 17:03 ` Björn Lindqvist
2016-11-28 16:13 ` Paul Eggert
2016-11-27 16:52 ` Stefan Monnier
2016-11-26 19:08 ` Pip Cet
2016-11-27 0:24 ` Paul Eggert
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