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 <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Eric Dumazet 2009-10-26 18:40:35 -07:00 • committed by David S. Miller
commit 05423b2413
5 changed files with 15 additions and 10 deletions

View file

@ -63,7 +63,11 @@ static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
return (struct vlan_ethhdr *)skb_mac_header(skb);
}
#define VLAN_VID_MASK 0xfff
#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 */
/* found in socket.c */
extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));
@ -105,8 +109,8 @@ static inline void vlan_group_set_device(struct vlan_group *vg,
array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] = dev;
}
#define vlan_tx_tag_present(__skb) ((__skb)->vlan_tci)
#define vlan_tx_tag_get(__skb) ((__skb)->vlan_tci)
#define vlan_tx_tag_present(__skb) ((__skb)->vlan_tci & VLAN_TAG_PRESENT)
#define vlan_tx_tag_get(__skb) ((__skb)->vlan_tci & ~VLAN_TAG_PRESENT)
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
@ -231,7 +235,7 @@ static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
static inline struct sk_buff *__vlan_hwaccel_put_tag(struct sk_buff *skb,
u16 vlan_tci)
{
skb->vlan_tci = vlan_tci;
skb->vlan_tci = VLAN_TAG_PRESENT | vlan_tci;
return skb;
}
@ -284,7 +288,7 @@ static inline int __vlan_hwaccel_get_tag(const struct sk_buff *skb,
u16 *vlan_tci)
{
if (vlan_tx_tag_present(skb)) {
*vlan_tci = skb->vlan_tci;
*vlan_tci = vlan_tx_tag_get(skb);
return 0;
} else {
*vlan_tci = 0;