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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 17:58:02 +0900	[thread overview]
Message-ID: <wlzmdypisl.wl%mituharu@math.s.chiba-u.ac.jp> (raw)
In-Reply-To: <44E972EC.8000903@swipnet.se>

>>>>> On Mon, 21 Aug 2006 10:46:36 +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.

> I don't see the line "what are interrupted by a signal" in the
> quote, so I'm not sure what you mean.

> My interpretation is that it is unsafe to call lock/unlock from a
> thread and from a signal handler at the same time, if they operate
> on the same mutex.  That is what the original hang was all about.

The standard says "when a signal interrupts an unsafe function ...".
My interpretation is that a signal interrupts *only* the function in
execution on the thread that the signal is delivered to, but the
signal does not interrupt the functions in execution on the other
threads.

>> 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.

> But this only works for the Emacs main thread, not the Gnome
> threads.

And according to the above interpretation, functions that are executed
on non-main threads are irrelevant.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

  reply	other threads:[~2006-08-21  8:58 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
2006-08-21  8:46             ` Jan Djärv
2006-08-21  8:58               ` YAMAMOTO Mitsuharu [this message]
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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