jamal wrote:
On Fri, 2006-30-06 at 16:15 +0200, Thomas Graf wrote:
You agreed in
your last posting that the 3rd option, being that not caring about
whether a device might disappear but having a way to check for it,
is what we agreed on and what makes most sense,
yes, i recalled that as the last discussion we had.
yet you fail to see
that using ifindex is exactly what reflects this descision.
The choice is between using an ifindex and a pointer to the device.
Why is it solvable via an ifindex but not a device pointer?
I may have misunderstood you, so look at this as a fresh opportunity to
enlighten me. Forget about all the discussion weve had thus far.
If you use a pointer, without taking it's reference, then that device
can go away, and leave you with a stale memory access, ie kernel crash
or worse.
If you take a reference for every packet (which means an atomic op), then
you slow down every packet, even those that will never use the reference.
If you instead use the if-index, then you do not need to take a reference
for every packet, but only when you actually want to look at that device.
If the device has since disappeared, then you get a null when trying to find
by reference, and the code can take appropriate action. No chance for
access of stale memory.
Ben
--
Ben Greear <[EMAIL PROTECTED]>
Candela Technologies Inc http://www.candelatech.com
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