Re: [PATCH] RCU: Reduce size of rcu_head 1 of 2

[Rusty Russell <rusty@rustcorp.com.au>]

In message <1059830126.19819.8.camel@dhcp22.swansea.linux.org.uk> you write:
> On Sad, 2003-08-02 at 02:49, Rusty Russell wrote:
> > Sure.  But it's not neccessary.  The replacement is cleaner and
> > smaller, sure, but it's not worth changing once 2.6 is out.  In 2.7,
> > sure.
> > 
> > I'm happy to accept "no" from Andrew, but not happy to accept "we'll
> > just change the API midway through 2.6".
> 
> Please distinguish API from ABI. There is no ABI, there is no need for
> an ABI.

You are confused, but it seems you are not alone.  I don't understand
where this talk of ABI came from.

There are two patches.  Both reduce the size of the "struct rcu_head".
One simply changes the struct rcu_head from a double linked list to a
single linked list.  The other eliminates the "void *data" arg, and
changes the prototype of the call_rcu() function to take a pointer to
the struct rcu_head, rather than a user-defined data ptr.

It is the latter that I am concerned about changing mid-stable-series.

Hope that clarifies,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.