[ovs-dev] [PATCH 2/3] netdev-linux: Give tap FD to first opener.

Ben Pfaff blp at nicira.com
Tue Jun 1 23:27:56 UTC 2010

On Tue, Jun 01, 2010 at 04:17:39PM -0700, Jesse Gross wrote:
> Tap devices can have two FDs that allow transmit and receive from
> different perspectives.  We previously would always share one of
> the FDs among all openers.  However, this is confusing to some
> users (primarily the DHCP client) which expect tap devices to behave
> like any other device.  Now we give the tap FD to the first opener,
> which knows that it has opened a tap device, and a normal system FD
> to everyone else for consistency.

I'm OK with this patch, but the need for it really makes me wonder
whether we have a conceptual problem with the implementation of TAP
devices.  When abstractions are correct, usually this kind of funny
special case is unnecessary.

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