On Sun, May 20, 2007 at 11:14:49PM +0200, Martin Husemann wrote:

> On Sun, May 20, 2007 at 01:58:23PM -0700, Matt Thomas wrote:
> > switchto(NULL, tmp); /* old is deleted *.
> > switchto(tmp, x);
> > 
> > if old was returned, it would be to a deleted lwp and that can't be  
> > right.
> 
> I don't understand. In the switchto(NULL, tmp) case - should it return
> NULL, or the lwp it is switching away from?
> 
> My reading of the man page says the latter, but code for the ports
> I checked does the former.

The latter: switchto(NULL, tmp) should return NULL. A null value is passed
in when an LWP is exiting. It's used as a hint to avoid some locking, and to
avoid saving any state (there's no point doing doing either).

Andrew