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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2009-10-27 04:40:35 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-10-27 11:02:33 +0300 |
| commit | 05423b241311c9380b7280179295bac7794281b6 (patch) | |
| tree | 8a84aca48cbc30b142bdf143dbf11fdbab9cad67 /drivers/uio/uio_sercos3.c | |
| parent | 9dbb58d867e90d2528752339751216c955523e62 (diff) | |
| download | linux-05423b241311c9380b7280179295bac7794281b6.tar.xz | |
vlan: allow null VLAN ID to be used
We currently use a 16 bit field (vlan_tci) to store VLAN ID/PRIO on a skb.
Null value is used as a special value, meaning vlan tagging not enabled.
This forbids use of null vlan ID.
As pointed by David, some drivers use the 3 high order bits (PRIO)
As VLAN ID is 12 bits, we can use the remaining bit (CFI) as a flag, and
allow null VLAN ID.
In case future code really wants to use VLAN_CFI_MASK, we'll have to use
a bit outside of vlan_tci.
#define VLAN_PRIO_MASK 0xe000 /* Priority Code Point */
#define VLAN_PRIO_SHIFT 13
#define VLAN_CFI_MASK 0x1000 /* Canonical Format Indicator */
#define VLAN_TAG_PRESENT VLAN_CFI_MASK
#define VLAN_VID_MASK 0x0fff /* VLAN Identifier */
Reported-by: Gertjan Hofman <gertjan_hofman@yahoo.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/uio/uio_sercos3.c')
0 files changed, 0 insertions, 0 deletions