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Message-ID: <20120824175616.GL2472@linux.vnet.ibm.com>
Date: Fri, 24 Aug 2012 10:56:16 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Vlad Yasevich <vyasevic@...hat.com>
Cc: netdev@...r.kernel.org
Subject: Re: [RFC PATCH bridge 4/5] bridge: Add private ioctls to configure
vlans on bridge ports
On Thu, Aug 23, 2012 at 03:29:54PM -0400, Vlad Yasevich wrote:
> Add a private ioctl to add and remove vlan configuration on bridge port.
>
> Signed-off-by: Vlad Yasevich <vyasevic@...hat.com>
One question below...
> ---
> include/linux/if_bridge.h | 2 +
> net/bridge/br_if.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
> net/bridge/br_ioctl.c | 31 ++++++++++++++++++++
> net/bridge/br_private.h | 2 +
> 4 files changed, 104 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
> index 288ff10..ab750dd 100644
> --- a/include/linux/if_bridge.h
> +++ b/include/linux/if_bridge.h
> @@ -42,6 +42,8 @@
> #define BRCTL_SET_PORT_PRIORITY 16
> #define BRCTL_SET_PATH_COST 17
> #define BRCTL_GET_FDB_ENTRIES 18
> +#define BRCTL_ADD_VLAN 19
> +#define BRCTL_DEL_VLAN 20
>
> #define BR_STATE_DISABLED 0
> #define BR_STATE_LISTENING 1
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index e1144e1..90c1038 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -23,6 +23,7 @@
> #include <linux/if_ether.h>
> #include <linux/slab.h>
> #include <net/sock.h>
> +#include <linux/if_vlan.h>
>
> #include "br_private.h"
>
> @@ -441,6 +442,74 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
> return 0;
> }
>
> +/* Called with RTNL */
> +int br_set_port_vlan(struct net_bridge_port *p, unsigned long vlan)
> +{
> + unsigned long table_size = (VLAN_N_VID/sizeof(unsigned long)) + 1;
> + unsigned long *vid_map = NULL;
> + __u16 vid = (__u16) vlan + 1;
> +
> + /* We are under lock so we can check this without rcu.
> + * The vlan map is indexed by vid+1. This way we can store
> + * vid 0 (untagged) into the map as well.
> + */
> + if (!p->vlan_map) {
> + vid_map = kzalloc(table_size, GFP_KERNEL);
> + if (!vid_map)
> + return -ENOMEM;
> +
> + set_bit(vid, vid_map);
> + rcu_assign_pointer(p->vlan_map, vid_map);
> +
> + } else {
> + /* Map is already allocated */
> + set_bit(vid, p->vlan_map);
> + }
> +
> + return 0;
> +}
> +
> +
> +/* Called with RTNL */
> +int br_del_port_vlan(struct net_bridge_port *p, unsigned long vlan)
> +{
> + unsigned long first_bit;
> + unsigned long next_bit;
> + __u16 vid = (__u16) vlan+1;
> + unsigned long tbl_len = VLAN_N_VID+1;
> +
> + if (!p->vlan_map)
> + return -EINVAL;
> +
> + if (!test_bit(vlan, p->vlan_map))
> + return -EINVAL;
> +
> + /* Check to see if any other vlans are in this table. If this
> + * is the last vlan, delete the whole table. If this is not the
> + * last vlan, just clear the bit.
> + */
> + first_bit = find_first_bit(p->vlan_map, tbl_len);
> + next_bit = find_next_bit(p->vlan_map, tbl_len, (tbl_len - vid));
> +
> + if ((__u16)first_bit != vid || (__u16)next_bit < tbl_len) {
> + /* There are other vlans still configured. We can simply
> + * clear our bit and be safe.
> + */
> + clear_bit(vid, p->vlan_map);
> + } else {
> + /* This is the last vlan we are removing. Replace the
> + * map with a NULL pointer and free the old map
> + */
> + unsigned long *map = rcu_dereference(p->vlan_map);
> +
> + rcu_assign_pointer(p->vlan_map, NULL);
> + synchronize_net();
> + kfree(map);
> + }
> +
> + return 0;
> +}
> +
> void __net_exit br_net_exit(struct net *net)
> {
> struct net_device *dev;
> diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
> index 7222fe1..3a5b1f9 100644
> --- a/net/bridge/br_ioctl.c
> +++ b/net/bridge/br_ioctl.c
> @@ -289,6 +289,37 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
> case BRCTL_GET_FDB_ENTRIES:
> return get_fdb_entries(br, (void __user *)args[1],
> args[2], args[3]);
> + case BRCTL_ADD_VLAN:
> + {
> + struct net_bridge_port *p;
> +
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + rcu_read_lock();
> + if ((p = br_get_port(br, args[1])) == NULL) {
> + rcu_read_unlock();
> + return -EINVAL;
> + }
> + rcu_read_unlock();
Why is it safe to pass "p" out of the RCU read-side critical section?
I don't see that br_get_port() does anything to make this safe, at least
not in v3.5.
> + return br_set_port_vlan(p, args[2]);
> + }
> +
> + case BRCTL_DEL_VLAN:
> + {
> + struct net_bridge_port *p;
> +
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + rcu_read_lock();
> + if ((p = br_get_port(br, args[1])) == NULL) {
> + rcu_read_unlock();
> + return -EINVAL;
> + }
> + rcu_read_unlock();
> + br_set_port_vlan(p, args[2]);
> + }
> }
>
> return -EOPNOTSUPP;
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index b6c56ab..5639c1c 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -402,6 +402,8 @@ extern int br_del_if(struct net_bridge *br,
> extern int br_min_mtu(const struct net_bridge *br);
> extern netdev_features_t br_features_recompute(struct net_bridge *br,
> netdev_features_t features);
> +extern int br_set_port_vlan(struct net_bridge_port *p, unsigned long vid);
> +extern int br_del_port_vlan(struct net_bridge_port *p, unsigned long vid);
>
> /* br_input.c */
> extern int br_handle_frame_finish(struct sk_buff *skb);
> --
> 1.7.7.6
>
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