Subject: Re: [RFC PATCH bridge 5/5] bridge: Add sysfs interface to display VLANS

From: Vlad Yasevich <[email-masked]>
Date: Thu, 30 Aug 2012 10:05:16 -0400

On 08/30/2012 08:27 AM, Michael S. Tsirkin wrote:
> On Thu, Aug 23, 2012 at 03:29:55PM -0400, Vlad Yasevich wrote:
>> Add a binary sysfs file that will dump out vlans currently configured on the
>> port.
>>
>> Signed-off-by: Vlad Yasevich <[email-masked]>
>
> So what's the format here? I could not tell.
> List of vlans? Why binary? Why not make it text in that case?
> This would also allow reporting "all" if filtering
> is disabled and "untagged" for untagged packets.

I decided to do binary because text may result in more then page worth 
of data.  The display tool will know how to display things properly.

-vlad

>
>> ---
>>   include/linux/if_bridge.h |    1 +
>>   net/bridge/br_if.c        |   34 ++++++++++++++++++++++++++++++++++
>>   net/bridge/br_private.h   |    2 ++
>>   net/bridge/br_sysfs_if.c  |   28 ++++++++++++++++++++++++++++
>>   4 files changed, 65 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
>> index ab750dd..d0f869b 100644
>> --- a/include/linux/if_bridge.h
>> +++ b/include/linux/if_bridge.h
>> @@ -20,6 +20,7 @@
>>   #define SYSFS_BRIDGE_PORT_SUBDIR "brif"
>>   #define SYSFS_BRIDGE_PORT_ATTR	"brport"
>>   #define SYSFS_BRIDGE_PORT_LINK	"bridge"
>> +#define SYSFS_BRIDGE_PORT_VLANS "vlans"
>>
>>   #define BRCTL_VERSION 1
>>
>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>> index 90c1038..3963748 100644
>> --- a/net/bridge/br_if.c
>> +++ b/net/bridge/br_if.c
>> @@ -510,6 +510,40 @@ int br_del_port_vlan(struct net_bridge_port *p, unsigned long vlan)
>>   	return 0;
>>   }
>>
>> +size_t br_port_fill_vlans(struct net_bridge_port *p, char* buf,
>> +			unsigned long max, unsigned long skip)
>> +{
>> +	unsigned long *map;
>> +	unsigned short *vid = (unsigned short *)buf;
>> +	unsigned short i;
>> +	int num = 0;
>> +
>> +	if (skip > (VLAN_N_VID+1))
>> +		return -EINVAL;
>> +
>> +	memset(buf, 0, max * sizeof(unsigned short));
>
> Isn't max is in bytes? why is this safe?
>
>> +
>> +	rcu_read_lock();
>> +	map = rcu_dereference(p->vlan_map);
>> +	if (!map)
>> +		goto out;
>> +
>> +	for (i = skip + 1; i < VLAN_N_VID + 1; i++) {
>
> Isn't skip in bytes too? Why do you compare it to i which is
> in dwords?
>
>> +		if (test_bit(i, map)) {
>> +			if (num > max)
>> +				goto out;
>> +
>> +			*vid = i-1;
>> +			vid++;
>> +			num++;
>> +		}
>> +	}
>> +out:
>> +	rcu_read_unlock();
>> +
>> +	return num*sizeof(unsigned short);
>> +}
>> +
>>   void __net_exit br_net_exit(struct net *net)
>>   {
>>   	struct net_device *dev;
>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>> index 5639c1c..cf95cd7 100644
>> --- a/net/bridge/br_private.h
>> +++ b/net/bridge/br_private.h
>> @@ -404,6 +404,8 @@ 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);
>> +extern size_t br_port_fill_vlans(struct net_bridge_port *p, char *buf,
>> +				unsigned long max, unsigned long skip);
>>
>>   /* br_input.c */
>>   extern int br_handle_frame_finish(struct sk_buff *skb);
>> diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
>> index 13b36bd..a81e2ef 100644
>> --- a/net/bridge/br_sysfs_if.c
>> +++ b/net/bridge/br_sysfs_if.c
>> @@ -234,6 +234,29 @@ const struct sysfs_ops brport_sysfs_ops = {
>>   };
>>
>>   /*
>> + * Export the vlan table for a given port as a binary file.
>> + * The records are unsgined shorts.
>> + *
>> + * Returns the number of bytes read.
>> + */
>> +static ssize_t brport_vlans_read(struct file *filp, struct kobject *kobj,
>> +				struct bin_attribute *bin_attr,
>> +				char *buf, loff_t off, size_t count)
>> +{
>> +	struct net_bridge_port *p = to_brport(kobj);
>> +
>> +	return br_port_fill_vlans(p, buf,
>> +				count/sizeof(unsigned short),
>> +				off/sizeof(unsigned short));
>> +}
>> +
>> +static struct bin_attribute port_vlans = {
>> +	.attr = { .name = SYSFS_BRIDGE_PORT_VLANS,
>> +		  .mode = S_IRUGO, },
>> +	.read = brport_vlans_read,
>> +};
>> +
>> +/*
>>    * Add sysfs entries to ethernet device added to a bridge.
>>    * Creates a brport subdirectory with bridge attributes.
>>    * Puts symlink in bridge's brif subdirectory
>> @@ -255,6 +278,11 @@ int br_sysfs_addif(struct net_bridge_port *p)
>>   			return err;
>>   	}
>>
>> +	err = sysfs_create_bin_file(&p->kobj, &port_vlans);
>> +	if (err) {
>> +		return err;
>> +	}
>> +
>>   	strlcpy(p->sysfs_name, p->dev->name, IFNAMSIZ);
>>   	return sysfs_create_link(br->ifobj, &p->kobj, p->sysfs_name);
>>   }
>> --
>> 1.7.7.6
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to [email-masked]
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html