netif_stop_all_queues must be called before calling H_FREE_LOGICAL_LAN.
As a result, we can remove the pool_config field from the ibmveth
adapter structure.

Some device configuration changes call ibmveth_close in order to free
the current resources held by the device. These functions then make
their changes and call ibmveth_open to reallocate and reserve resources
for the device.

Prior to this commit, the flag pool_config was used to tell ibmveth_close
that it should not halt the transmit queue. pool_config was introduced in
commit 860f242e ("[PATCH] ibmveth change buffer pools dynamically")
to avoid interrupting the tx flow when making rx config changes. Since
then, other commits adopted this approach, even if making tx config
changes.

The issue with this approach was that the hypervisor freed all of
the devices control structures after the hcall H_FREE_LOGICAL_LAN
was performed but the transmit queues were never stopped. So the higher
layers in the network stack would continue transmission but any
H_SEND_LOGICAL_LAN hcall would fail with H_PARAMETER until the
hypervisor's structures for the device were allocated with the
H_REGISTER_LOGICAL_LAN hcall in ibmveth_open. This resulted in
no real networking harm but did cause several of these error
messages to be logged: "h_send_logical_lan failed with rc=-4"

So, instead of trying to keep the transmit queues alive during network
configuration changes, just stop the queues, make necessary changes then
restart the queues.
Signed-off-by: Nick Child <nnac123@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>