Subject: Re: [RFC PATCH 06/24] net: rbridge: Enable/disable TRILL capability

From: Vlad Yasevich <[email-masked]>
Date: Wed, 24 Sep 2014 13:46:37 -0400

On 09/24/2014 11:52 AM, Ahmed Amamou wrote:
> enable switching TRILL capability state via sysfs command
> 
> Signed-off-by: Ahmed Amamou <[email-masked]>
> Signed-off-by: Kamel Haddadou <[email-masked]>
> ---
>  net/bridge/Makefile      |  2 ++
>  net/bridge/br_private.h  |  5 ++++
>  net/bridge/br_sysfs_br.c | 38 +++++++++++++++++++++++
>  net/bridge/rbridge/rbr.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 123 insertions(+)
>  create mode 100644 net/bridge/rbridge/rbr.c
> 
> diff --git a/net/bridge/Makefile b/net/bridge/Makefile
> index 8590b94..314783c 100644
> --- a/net/bridge/Makefile
> +++ b/net/bridge/Makefile
> @@ -17,3 +17,5 @@ bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o
>  bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o
>  
>  obj-$(CONFIG_NETFILTER) += netfilter/
> +
> +bridge-$(CONFIG_TRILL) += rbridge/rbr.o
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 430c556..844c87b 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -811,6 +811,11 @@ int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio);
>  int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost);
>  ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id);
>  
> +/* rbridge/rbr.c */
> +#ifdef CONFIG_TRILL
> +void br_trill_set_enabled(struct net_bridge *br, unsigned long val);
> +#endif
> +
>  /* br_stp_bpdu.c */
>  struct stp_proto;
>  void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
> diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
> index c9e2572..787ab84 100644
> --- a/net/bridge/br_sysfs_br.c
> +++ b/net/bridge/br_sysfs_br.c
> @@ -146,6 +146,41 @@ static ssize_t stp_state_store(struct device *d,
>  }
>  static DEVICE_ATTR_RW(stp_state);
>  
> +#ifdef CONFIG_TRILL
> +static ssize_t trill_state_show(struct device *d,
> +				struct device_attribute *attr, char *buf)
> +{
> +	struct net_bridge *br = to_bridge(d);
> +	return sprintf(buf, "%d\n", br->trill_enabled);
> +}
> +
> +static ssize_t trill_state_store(struct device *d,
> +				 struct device_attribute *attr, const char *buf,
> +				 size_t len)
> +{
> +	struct net_bridge *br = to_bridge(d);
> +	char *endp;
> +	unsigned long val;
> +
> +	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
> +		return -EPERM;
> +
> +	val = simple_strtoul(buf, &endp, 0);
> +	if (endp == buf)
> +		return -EINVAL;
> +
> +	if (!rtnl_trylock())
> +		return restart_syscall();
> +	br_trill_set_enabled(br, val);
> +	rtnl_unlock();
> +
> +	return len;
> +}
> +
> +static DEVICE_ATTR_RW(trill_state);
> +#endif
> +
> +
>  static ssize_t group_fwd_mask_show(struct device *d,
>  				   struct device_attribute *attr,
>  				   char *buf)
> @@ -733,6 +768,9 @@ static struct attribute *bridge_attrs[] = {
>  	&dev_attr_max_age.attr,
>  	&dev_attr_ageing_time.attr,
>  	&dev_attr_stp_state.attr,
> +#ifdef CONFIG_TRILL
> +	&dev_attr_trill_state.attr,
> +#endif
>  	&dev_attr_group_fwd_mask.attr,
>  	&dev_attr_priority.attr,
>  	&dev_attr_bridge_id.attr,
> diff --git a/net/bridge/rbridge/rbr.c b/net/bridge/rbridge/rbr.c
> new file mode 100644
> index 0000000..41d47db
> --- /dev/null
> +++ b/net/bridge/rbridge/rbr.c
> @@ -0,0 +1,78 @@
> +/*
> + *	Generic parts
> + *	Linux ethernet Rbridge
> + *
> + *	Authors:
> + *	Ahmed AMAMOU	<[email-masked]>
> + *	Kamel Haddadou	<[email-masked]>
> + *
> + *	This program is free software; you can redistribute it and/or
> + *	modify it under the terms of the GNU General Public License
> + *	as published by the Free Software Foundation; either version
> + *	2 of the License, or (at your option) any later version.
> + */
> +#include "br_private.h"
> +#include "rbr_private.h"
> +
> +static struct rbr *add_rbr(struct net_bridge *br)
> +{
> +	struct rbr *rbr;
> +
> +	if (!br->rbr) {
> +		rbr = kzalloc(sizeof(*rbr), GFP_KERNEL);
> +		if (!rbr)
> +			return NULL;
> +
> +		rbr->br = br;
> +		rbr->nick = RBRIDGE_NICKNAME_NONE;
> +		rbr->treeroot = RBRIDGE_NICKNAME_NONE;
> +		return rbr;
> +	}
> +
> +	return br->rbr;
> +}
> +
> +static void br_trill_start(struct net_bridge *br)
> +{
> +	/* Disable STP if it is already enabled */
> +
> +	if (br->stp_enabled != BR_NO_STP)
> +		br_stp_set_enabled(br, false);
> +	br->rbr = add_rbr(br);
> +	if (br->rbr) {
> +		spin_lock_bh(&br->lock);
> +		br->trill_enabled = BR_TRILL;
> +		spin_unlock_bh(&br->lock);
> +	} else {
> +		printk(KERN_WARNING
> +		       "RBridge allocation for bridge '%s' failed\n",
> +		       br->dev->name);
> +	}
> +}
> +
> +static void br_trill_stop(struct net_bridge *br)
> +{
> +	struct rbr *old;
> +
> +	spin_lock_bh(&br->lock);
> +	br->trill_enabled = BR_NO_TRILL;
> +	spin_unlock_bh(&br->lock);

Are the locks around trill_enabled really needed?  Seems to be already
protected by rtnl.  Are you protecting against something else?

> +	old = br->rbr;
> +	br->rbr = NULL;
> +	if (likely(old)) {
> +		spin_lock_bh(&br->lock);
> +		kfree(old);
> +		spin_unlock_bh(&br->lock);

These locks appear to be completely unnecessary.

Also what's protecting future refrences to br->rbr?  Should it be rcu
protected?

-vlad
> +	}
> +}
> +
> +void br_trill_set_enabled(struct net_bridge *br, unsigned long val)
> +{
> +	if (val) {
> +		if (br->trill_enabled == BR_NO_TRILL)
> +			br_trill_start(br);
> +	} else {
> +		if (br->trill_enabled != BR_NO_TRILL)
> +			br_trill_stop(br);
> +	}
> +}
>