Re: [PATCH v2] VLAN, support ingress/egress priority map flushing

[Thierry Du Tre]

On 13-03-17 16:28, Eric Dumazet wrote:

On Mon, 2017-03-13 at 15:36 +0100, Thierry Du Tre wrote:


+void vlan_dev_flush_egress_priority(const struct net_device *dev)
+{
+   struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+   struct vlan_priority_tci_mapping *mp;
+   int i;
+
+   for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
+   while ((mp = vlan->egress_priority_map[i]) != NULL) {
+   vlan->egress_priority_map[i] = mp->next;
+   kfree(mp);
+   }
+   }
+   vlan->nr_egress_mappings = 0;
+}


Are you doing this on a live device ?

Looks you'll need proper RCU support then.

Otherwise, crashes will happen, say in egress_priority_map()

smp_rmb() wont be enough if items can now be destroyed.

Yes, good point about the smp concurrency.
I wrongly assumed there was already some locking mechanism in place to 
protect these structures.


Let me take a look at this and I'll come back with a new proposal.

--
Thierry

Re: [PATCH v2] VLAN, support ingress/egress priority map flushing

[Eric Dumazet]

On Mon, 2017-03-13 at 15:36 +0100, Thierry Du Tre wrote:

> +void vlan_dev_flush_egress_priority(const struct net_device *dev)
> +{
> + struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
> + struct vlan_priority_tci_mapping *mp;
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
> + while ((mp = vlan->egress_priority_map[i]) != NULL) {
> + vlan->egress_priority_map[i] = mp->next;
> + kfree(mp);
> + }
> + }
> + vlan->nr_egress_mappings = 0;
> +}


Are you doing this on a live device ?

Looks you'll need proper RCU support then.

Otherwise, crashes will happen, say in egress_priority_map()

smp_rmb() wont be enough if items can now be destroyed.

[PATCH v2] VLAN, support ingress/egress priority map flushing

[Thierry Du Tre]

When sending packets via a vlan device we can manipulate the priority bits in 
the vlan header (PCP) via a mapping based on tc class value.
Similarly, when packets are received via a vlan device, the PCP value can be 
mapped onto a tc class value, which is available for iptables rules and tc 
queueing disciplines.

One can use the vconfig utility to set both ingress and egress mapping entries 
(set_ingress_map/set_egress_map) or any other application to call the vlan 
ioctl handler.

The resulting map can be printed via /proc/net/vlan/ , i.e. :
# cat /proc/net/vlan/vlan11
vlan11  VID: 11  REORDER_HDR: 1  dev->priv_flags: 1
 total frames received 52331849
  total bytes received  17451834908
  Broadcast/Multicast Rcvd  1525155

  total frames transmitted 98569270
   total bytes transmitted 144870211289
Device: eth_test
INGRESS priority mappings: 0:0  1:1  2:2  3:3  4:0  5:0  6:0 7:0
 EGRESS priority mappings: 0:7

The current API offers only GET and SET operations, and when actually using 
this functionality a flush is missing to reset all entries.
This patch adds a FLUSH operation for both ingress and egress map which can 
then be used by vconfig or other applications.

Signed-off-by: Thierry Du Tre 
---
Changes in v2:
  - Move new vlan cmd values to end of enum list.

 include/uapi/linux/if_vlan.h |  4 +++-
 net/8021q/vlan.c | 16 
 net/8021q/vlan.h |  2 ++
 net/8021q/vlan_dev.c | 23 +++
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/if_vlan.h b/include/uapi/linux/if_vlan.h
index 7e5e6b3..8daea77 100644
--- a/include/uapi/linux/if_vlan.h
+++ b/include/uapi/linux/if_vlan.h
@@ -27,7 +27,9 @@ enum vlan_ioctl_cmds {
SET_VLAN_NAME_TYPE_CMD,
SET_VLAN_FLAG_CMD,
GET_VLAN_REALDEV_NAME_CMD, /* If this works, you know it's a VLAN 
device, btw */
-   GET_VLAN_VID_CMD /* Get the VID of this VLAN (specified by name) */
+   GET_VLAN_VID_CMD, /* Get the VID of this VLAN (specified by name) */
+   FLUSH_VLAN_INGRESS_PRIORITY_CMD,
+   FLUSH_VLAN_EGRESS_PRIORITY_CMD
 };
 
 enum vlan_flags {

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 467069b..8988419 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -539,6 +539,22 @@ static int vlan_ioctl_handler(struct net *net, void __user 
*arg)
}
 
 	switch (args.cmd) {

+   case FLUSH_VLAN_INGRESS_PRIORITY_CMD:
+   err = -EPERM;
+   if (!capable(CAP_NET_ADMIN))
+   break;
+   vlan_dev_flush_ingress_priority(dev);
+   err = 0;
+   break;
+
+   case FLUSH_VLAN_EGRESS_PRIORITY_CMD:
+   err = -EPERM;
+   if (!capable(CAP_NET_ADMIN))
+   break;
+   vlan_dev_flush_egress_priority(dev);
+   err = 0;
+   break;
+
case SET_VLAN_INGRESS_PRIORITY_CMD:
err = -EPERM;
if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index df8bd65..d8d90ca 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h
@@ -97,6 +97,8 @@ static inline struct net_device *vlan_find_dev(struct 
net_device *real_dev,
(i) % VLAN_N_VID)))
 
 /* found in vlan_dev.c */

+void vlan_dev_flush_ingress_priority(const struct net_device *dev);
+void vlan_dev_flush_egress_priority(const struct net_device *dev);
 void vlan_dev_set_ingress_priority(const struct net_device *dev,
   u32 skb_prio, u16 vlan_prio);
 int vlan_dev_set_egress_priority(const struct net_device *dev,
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index e97ab82..8fd91c3 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -159,6 +159,29 @@ static int vlan_dev_change_mtu(struct net_device *dev, int 
new_mtu)
return 0;
 }
 
+void vlan_dev_flush_ingress_priority(const struct net_device *dev)

+{
+   struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+
+   memset(vlan->ingress_priority_map, 0, 
sizeof(vlan->ingress_priority_map));
+   vlan->nr_ingress_mappings = 0;
+}
+
+void vlan_dev_flush_egress_priority(const struct net_device *dev)
+{
+   struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+   struct vlan_priority_tci_mapping *mp;
+   int i;
+
+   for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
+   while ((mp = vlan->egress_priority_map[i]) != NULL) {
+   vlan->egress_priority_map[i] = mp->next;
+   kfree(mp);
+   }
+   }
+   vlan->nr_egress_mappings = 0;
+}
+
 void vlan_dev_set_ingress_priority(const struct net_device *dev,
   u32 skb_prio, u16 vlan_prio)
 {
--
2.7.4