Re: [RFC] add rtnl semaphore to linux-atm

["David S. Miller" <davem@xxxxxxxxxx>]

On Wed, 01 Oct 2003 09:07:45 -0400
chas williams <chas@xxxxxxxxxxxxxxxx> wrote:

> i had initially written it that way but remembered at one point i
> was going to use the rtnl semaphore to handle this problem.  any
> opinions on what is 'better'?

Blocking all network configuration operations (even ones not
for your subsystem) is a little bit anti-social in SMP cases.

If you take the rwlock as a reader, you only interfere with a
very minute class of network configuration code paths (those that
need to take the rwlock in question as a writer).

For example, if you use the rwlock-as-reader approach, someone doing
IPV4 routing table updates (ie. routing daemon changing a couple
thousand routes after a BGP flap) won't be perturbed while the ATM
operation is in progress.