Re: [RFC,PATCH] Use RCU to protect tasklist for unicast signals

[Dipankar Sarma <dipankar@in.ibm.com>]

On Thu, Aug 11, 2005 at 06:14:51PM +0100, Christoph Hellwig wrote:
> On Wed, Aug 10, 2005 at 10:11:45AM -0700, Paul E. McKenney wrote:
> > Hello!
> > 
> > This patch is an experiment in use of RCU for individual code paths that
> > read-acquire the tasklist lock, in this case, unicast signal delivery.
> > It passes five kernbenches on 4-CPU x86, but obviously needs much more
> > testing before it is considered for serious use, let alone inclusion.
> 
> I think we should switch over tasklist_lock to RCU completely instead of
> adding suck hacks.  I've started lots of preparation work to get rid of
> tasklist_lock users outside of kernel/, especialy getting rid of any
> use in modules.

That would be really helpful, specially the ones in drivers/char/tty*.c :)

When I worked on this last (a year or so ago), it seemed that I would
need to put a number of additional structures under RCU control.
It would be better to gradually move it towards RCU rather than
trying make all the readers lock-free.

Thanks
Dipankar