VLAN issues

[Sepherosa Ziehau]

On 3/26/07, Matthew Dillon <dillon at apollo.backplane.com> wrote:
    One thing I noticed about this patch is that there might be a logic
    error when clearing vlan flags.
    Lets say you have four vlan's, and you turn on promiscuous mode on two
    of them.  This propogates to the parent.   But now what happens if you
    turn off promiscuous mode on one of them?  Will it turn off promiscuous
    mode in the parent even though there is still one vlan interface left
    with it turned on?
    Also, if someone turns on promisc mode on the parent, and then turns it
    on for a vlan interface, then turns it off for a vlan interface, will
    it turn off the mode on the parent?  We wouldn't want it to.
    Another example... bridging turns on promiscuous mode.  But if an
    interface is bridged, and someone tcpdump's a vlan under that interface,
    then stops the tcpdump, will that turn off the interface's promiscuous
    mode?  Again we wouldn't want it to.
IFF_PROMISC is reference counted by ifnet.if_pcount, so the problems
you described do not exist :)
Best Regards,
sephe
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