>
>
> On Thu, 7 Jan 1999, Kenneth Albanowski wrote:
> > >
> > > wake_up(&mm->sleep);
> > >
> > > at the top of the function.
> >
> > You'll also need a wake_up in kernel/exit.c.
>
> No, exit_mm will call mmput(), so that will do the wakeup as far as I can
> tell.
Ah, yes, I see. I'm still stuck at 2.0.x, so I'm not familiar with the new
arrangement, but that makes a lot more sense.
> > > if (child > 0) {
> > > while (current->mm->count > 1)
> > > sleep_on(current->mm->sleep);
> > > }
> > > return child;
> > > }
> >
> > Interesting. Did you have a particular reason to expect this loop to be
> > triggered?
>
> No, as I disabled the recursive thing anyway. With a recursive thing you
> need a while loop, but the above wouldn't work anyway (the "1" is no
> longer a one at all). So you could certainly change the 'while' into an
> 'if'.
Come to think of it, though, one thread (of a bunch that are using the
same mm) ought to be able to vfork(), even if more then one can't. Maybe
add a mutex around the sleep (this doesn't involve recursion, just
multithreading, so deadlock shouldn't be too much of an issue), or give up
and move the sleep wait_queue into the task_struct. Might need another
count to prevent recursion, though.
Before anyone asks, yes, this is almost a real-world issue. If I had
needed to speed up a uClinux httpd much more, it would have been
multi-threaded, and it was already CGI capable...
-- Kenneth Albanowski (kjahds@kjahds.com, CIS: 70705,126)
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