From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>, emacs-devel@gnu.org
Subject: Re: why "in_sighandler"?
Date: Mon, 21 Aug 2006 17:13:21 +0900 [thread overview]
Message-ID: <wl3bbqqzfi.wl%mituharu@math.s.chiba-u.ac.jp> (raw)
In-Reply-To: <44E95E71.30203@swipnet.se>
>>>>> On Mon, 21 Aug 2006 09:19:13 +0200, Jan Djärv <jan.h.d@swipnet.se> said:
> Read the single exception: "when a signal interrupts an unsafe
> function and the signal-catching function calls an unsafe function,
> the behavior is undefined."
So, you interpret that ``what are interrupted by a signal'' are all
the functions in execution on the whole threads in the process, not
just a single function in execution on the thread that the signal is
delivered to? I don't think that is a natural interpretation.
> No, but in the presense of signal handlers executing malloc, there
> is no scenario that is safe. Your suggestion also has undefined
> behaviour accoding to the quote from the standard.
As I said earlier, the current Emacs implementation calls malloc
within a signal handler with the help of BLOCK_INPUT relying on the
assumption that it is safe unless the signal interrupted
malloc-related functions. As malloc also internally uses some mutex
in order to make it thread-safe, I don't think allowing mutex
operations in a signal handler (with the help of BLOCK_INPUT, of
course) makes the situation worse.
>> Suppose that we abandon emacs_blocked_malloc and so on when
>> HAVE_GTK_AND_PTHREAD is defined. I think it is as safe as other
>> non-GNU-malloc systems where emacs_blocked_malloc and so on are not
>> used, provided that malloc-related functions are thread-safe. What
>> do you think about that?
> This whole workaround with mutexes and blocks started because Emacs
> hanged on some system, I'm not sure if it was a GNU/Linux system or
> some kind of BSD variant. So I don't think we should go back, the
> old problem happend every time the file selection box was opened on
> a Gnome system.
Do you mean this one?
http://lists.gnu.org/archive/html/emacs-pretest-bug/2004-11/msg00368.html
Then it's on a GNU/Linux system and emacs_blocked_malloc has already
existed and used, and we've never tried to abandon
emacs_blocked_malloc etc. I think BSD variants don't use them by
default anyway.
YAMAMOTO Mitsuharu
mituharu@math.s.chiba-u.ac.jp
next prev parent reply other threads:[~2006-08-21 8:13 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-20 6:51 why "in_sighandler"? Stefan Monnier
2006-08-20 16:37 ` Jan D.
2006-08-20 18:22 ` Stefan Monnier
2006-08-21 0:08 ` YAMAMOTO Mitsuharu
2006-08-21 6:18 ` Jan Djärv
2006-08-21 6:44 ` YAMAMOTO Mitsuharu
2006-08-21 7:19 ` Jan Djärv
2006-08-21 8:13 ` YAMAMOTO Mitsuharu [this message]
2006-08-21 8:46 ` Jan Djärv
2006-08-21 8:58 ` YAMAMOTO Mitsuharu
2006-08-21 11:32 ` Jan Djärv
2006-08-22 0:22 ` YAMAMOTO Mitsuharu
2006-08-22 6:38 ` Jan Djärv
2006-08-22 7:39 ` YAMAMOTO Mitsuharu
2006-08-22 8:23 ` Jan Djärv
2006-08-22 8:34 ` YAMAMOTO Mitsuharu
2006-08-22 18:00 ` Jan Djärv
2006-08-22 9:43 ` Andreas Schwab
2006-08-21 11:13 ` Richard Stallman
2006-08-21 12:55 ` Jan Djärv
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