Re: [PATCH 3/8] net: Add Generic Receive Offload infrastructure

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Tue, Dec 16, 2008 at 01:04:32PM +1100, Herbert Xu wrote:
> On Mon, Dec 15, 2008 at 03:39:20PM -0800, David Miller wrote:
> > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> >
> > > Presumably ptype_base[] is a static array rather than a dynamically
> > > allocated array that is resized under RCU protection, right?  Otherwise,
> > > you could get in trouble if the above raced with the resize operation due
> > > to the fact that you are outside of the RCU read-side critical section.
> > 
> > Yes, and we've been using RCU this way for this table for quite
> > some time.  From net/core/dev.c:
> > 
> > #define PTYPE_HASH_SIZE	(16)
> > #define PTYPE_HASH_MASK	(PTYPE_HASH_SIZE - 1)
> > 
> > static DEFINE_SPINLOCK(ptype_lock);
> > static struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
> > static struct list_head ptype_all __read_mostly;	/* Taps */
> 
> Thanks for confirming.  Yes unless there is a sudden surge of
> new Ethernet protocols we shouldn't need to resize this ever :)

;-)

						Thanx, Paul