bug#45898: 27.1; wedged in redisplay again

[Gerd Möllmann]

> On 2022-06-25,, at 11:57 , Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Date: Sat, 25 Jun 2022 11:49:42 +0200
>> Cc: 45898@debbugs.gnu.org
>> 
>> Or maybe "ticks" is already a good enough name?  We could then simply have 
>> update_ticks and good.  Or eticks to not confuse it with time ticks, if that 
>> ever happens.
> 
> You mean, just update_ticks?  That's too general, IMO.  I'd like
> people to have an idea what that does when they just see the call.
> 
> But I'm not good with names.

I love update_ticks!  And I'm good with names, trust me ;-).  And I'm 
volunteering to do the work!

>> You mean a case, where small numbers of ticks sum up by calling these Lisp 
>> functions often enough?
> 
> Actually, I meant something even simpler: a Lisp program that calls,
> say, regexp search repeatedly, to accumulate enough ticks that would
> signal an error, thus aborting that Lisp program.

That's 100% what I also meant.  Sorry for not being clear.

Do you think redisplaying_p would suffice as an indicator?  

That should be true if and only if redisplay_internal is in the call stack.  
Also, redisplay_internal is a no-op if called recursively.  Or better said, 
both used to be the case.