Subject: Re: netdev ioctl & dev_base_lock : bad idea ?

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 09 Dec 2004 17:22:13 +1100

On Wed, 2004-12-08 at 22:06 -0800, David S. Miller wrote:
> On Fri, 26 Nov 2004 19:48:49 +1100
> Benjamin Herrenschmidt <[email-masked]> wrote:
> 
> > I suppose there is a good reason we can't just use the rtnl_sem for
> > these guys, though why isn't dev_base_lock a read/write semaphore
> > instead of a spinlock ? At least on ppc, I don't think there's any
> > overhead in the normal path, and this is not on a very critical path
> > anyway, is it ?
> 
> It can't be a semphore because it is taken in packet processing,
> and thus softint handling, paths.

Right, and I missed the fact that we did indeed take the semaphore and
not the lock in the _set_ functions which is just fine, we can actually
schedule.... except in set_multicast...

Is there any reason we actually _need_ to get the xmit lock in this one
specifically ?

Ben.