On 6/13/2013 1:54 PM, Robert Love wrote:
fcoe_xmit was coded such that it would skip the vlan net device/layer
and instead set some vlan flags and transmit on the real net device.
The real net device has code that would add the vlan tag for fcoe skbs.
This avoids some extra processing for data frames and provides a small
performance improvement.
Since fcoe_xmit was not using the vlan net device, __vlan_put_tag
within the real net device's xmit routine was ultimately being
called to set the vlan tag.
With the below change the behavior of __vlan_put_tag changed slightly,
it now sets the skb->protocol = vlan_proto. vlan_proto was not a field
being set by fcoe_xmit, so the skb->protocol is now not being set to
ETH_P_8021Q, as it should be.
This patch converts fcoe_xmit to use the vlan_put_tag routine which
will tag the skb and fcoe will continue to transmit fcoe skbs on the
real net device.
For reference, the below change was the one that altered the
__vlan_put_tag behavior.
commit 86a9bad3ab6b6f858fd4443b48738cabbb6d094c
Author: Patrick McHardy <[email protected]>
Date: Fri Apr 19 02:04:30 2013 +0000
net: vlan: add protocol argument to packet tagging functions
Add a protocol argument to the VLAN packet tagging functions. In case of
HW
tagging, we need that protocol available in the ndo_start_xmit functions,
so it is stored in a new field in the skb. The new field fits into a hole
(on 64 bit) and doesn't increase the sks's size.
Signed-off-by: Robert Love <[email protected]>
Acked-by: Neil Horman <[email protected]>
Tested-by: Ross Brattain <[email protected]>
---
drivers/scsi/fcoe/fcoe.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index fc7bb1f..cb7ac9c 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1658,13 +1658,11 @@ static int fcoe_xmit(struct fc_lport *lport, struct
fc_frame *fp)
skb->protocol = htons(ETH_P_FCOE);
skb->priority = fcoe->priority;
- if (fcoe->netdev->priv_flags & IFF_802_1Q_VLAN &&
- fcoe->realdev->features & NETIF_F_HW_VLAN_CTAG_TX) {
- skb->vlan_tci = VLAN_TAG_PRESENT |
- vlan_dev_vlan_id(fcoe->netdev);
- skb->dev = fcoe->realdev;
- } else
- skb->dev = fcoe->netdev;
+ /* must set skb->dev before calling vlan_put_tag */
+ skb->dev = fcoe->realdev;
Should there be a check to see if a vlan tag is needed? I'm not sure
but is there ever a case where we really want to run over the real
device without any tag?
With this new block a tag will always be inserted perhaps a zero id tag.
+ skb = vlan_put_tag(skb, htons(ETH_P_8021Q),
vlan_dev_vlan_id(fcoe->netdev));
Also and likely more importantly I think this may do a bad pointer
dereference if fcoe->netdev is not a vlan dev. Just take a look at
vlan_dev_vlan_id in ./net/8021q/vlan_core.c
+ if (!skb)
+ return -ENOMEM;
/* fill up mac and fcoe headers */
eh = eth_hdr(skb);
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