Re: why "in_sighandler"?

[YAMAMOTO Mitsuharu]

>>>>> On Mon, 21 Aug 2006 10:46:36 +0200, Jan Djärv <address@hidden> 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
                                address@hidden