sfc: detach from cb_page in efx_copy_channel()

It's a resource, not a parameter, so we can't copy it into the new
 channel's TX queues, otherwise aliasing will lead to resource-
 management bugs if the channel is subsequently torn down without
 being initialised.

Before the Fixes:-tagged commit there was a similar bug with
 tsoh_page, but I'm not sure it's worth doing another fix for such
 old kernels.

Fixes: e9117e5099ea ("sfc: Firmware-Assisted TSO version 2")
Suggested-by: Derek Shute <Derek.Shute@stratus.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c
index aeb5e8a..73d4e39 100644 (file)
--- a/drivers/net/ethernet/sfc/efx_channels.c
+++ b/drivers/net/ethernet/sfc/efx_channels.c
@@ -583,6 +583,7 @@ struct efx_channel *efx_copy_channel(const struct efx_channel *old_channel)
                if (tx_queue->channel)
                        tx_queue->channel = channel;
                tx_queue->buffer = NULL;
+               tx_queue->cb_page = NULL;
                memset(&tx_queue->txd, 0, sizeof(tx_queue->txd));
        }