Date:   Mon, 25 Sep 2017 09:19:21 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Jiri Pirko <jiri@...nulli.us>, <netdev@...r.kernel.org>
CC:     <davem@...emloft.net>, <yotamg@...lanox.com>,
        <idosch@...lanox.com>, <mlxsw@...lanox.com>,
        <nikolay@...ulusnetworks.com>, <andrew@...n.ch>
Subject: Re: [patch net-next v2 03/12] ipmr: Add FIB notification access
 functions

Hi, Jiri

On 2017/9/25 1:22, Jiri Pirko wrote:
> From: Yotam Gigi <yotamg@...lanox.com>
> 
> Make the ipmr module register as a FIB notifier. To do that, implement both
> the ipmr_seq_read and ipmr_dump ops.
> 
> The ipmr_seq_read op returns a sequence counter that is incremented on
> every notification related operation done by the ipmr. To implement that,
> add a sequence counter in the netns_ipv4 struct and increment it whenever a
> new MFC route or VIF are added or deleted. The sequence operations are
> protected by the RTNL lock.
> 
> The ipmr_dump iterates the list of MFC routes and the list of VIF entries
> and sends notifications about them. The entries dump is done under RCU
> where the VIF dump uses the mrt_lock too, as the vif->dev field can change
> under RCU.
> 
> Signed-off-by: Yotam Gigi <yotamg@...lanox.com>
> Reviewed-by: Ido Schimmel <idosch@...lanox.com>
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
> ---
> v1->v2:
>  - Take the mrt_lock when dumping VIF entries.
> ---
>  include/linux/mroute.h   |  15 ++++++
>  include/net/netns/ipv4.h |   3 ++
>  net/ipv4/ipmr.c          | 137 ++++++++++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 153 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mroute.h b/include/linux/mroute.h
> index 10028f2..54c5cb8 100644
> --- a/include/linux/mroute.h
> +++ b/include/linux/mroute.h
> @@ -5,6 +5,7 @@
>  #include <linux/pim.h>
>  #include <linux/rhashtable.h>
>  #include <net/sock.h>
> +#include <net/fib_notifier.h>
>  #include <uapi/linux/mroute.h>
>  
>  #ifdef CONFIG_IP_MROUTE
> @@ -58,6 +59,14 @@ struct vif_device {
>  	int		link;			/* Physical interface index	*/
>  };
>  
> +struct vif_entry_notifier_info {
> +	struct fib_notifier_info info;
> +	struct net_device *dev;
> +	vifi_t vif_index;
> +	unsigned short vif_flags;
> +	u32 tb_id;
> +};
> +
>  #define VIFF_STATIC 0x8000
>  
>  #define VIF_EXISTS(_mrt, _idx) ((_mrt)->vif_table[_idx].dev != NULL)
> @@ -146,6 +155,12 @@ struct mfc_cache {
>  	struct rcu_head	rcu;
>  };
>  
> +struct mfc_entry_notifier_info {
> +	struct fib_notifier_info info;
> +	struct mfc_cache *mfc;
> +	u32 tb_id;
> +};
> +
>  struct rtmsg;
>  int ipmr_get_route(struct net *net, struct sk_buff *skb,
>  		   __be32 saddr, __be32 daddr,
> diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
> index 8387f09..abc84d9 100644
> --- a/include/net/netns/ipv4.h
> +++ b/include/net/netns/ipv4.h
> @@ -163,6 +163,9 @@ struct netns_ipv4 {
>  	struct fib_notifier_ops	*notifier_ops;
>  	unsigned int	fib_seq;	/* protected by rtnl_mutex */
>  
> +	struct fib_notifier_ops	*ipmr_notifier_ops;

Can we add a const here?

> +	unsigned int	ipmr_seq;	/* protected by rtnl_mutex */
> +
>  	atomic_t	rt_genid;
>  };
>  #endif
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 86dc5f9..49879c3 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -264,6 +264,16 @@ static void __net_exit ipmr_rules_exit(struct net *net)
>  	fib_rules_unregister(net->ipv4.mr_rules_ops);
>  	rtnl_unlock();
>  }
> +
> +static int ipmr_rules_dump(struct net *net, struct notifier_block *nb)
> +{
> +	return fib_rules_dump(net, nb, RTNL_FAMILY_IPMR);
> +}
> +
> +static unsigned int ipmr_rules_seq_read(struct net *net)
> +{
> +	return fib_rules_seq_read(net, RTNL_FAMILY_IPMR);
> +}
>  #else
>  #define ipmr_for_each_table(mrt, net) \
>  	for (mrt = net->ipv4.mrt; mrt; mrt = NULL)
> @@ -298,6 +308,16 @@ static void __net_exit ipmr_rules_exit(struct net *net)
>  	net->ipv4.mrt = NULL;
>  	rtnl_unlock();
>  }
> +
> +static int ipmr_rules_dump(struct net *net, struct notifier_block *nb)
> +{
> +	return 0;
> +}
> +
> +static unsigned int ipmr_rules_seq_read(struct net *net)
> +{
> +	return 0;
> +}
>  #endif
>  
>  static inline int ipmr_hash_cmp(struct rhashtable_compare_arg *arg,
> @@ -587,6 +607,43 @@ static struct net_device *ipmr_reg_vif(struct net *net, struct mr_table *mrt)
>  }
>  #endif
>  
> +static int call_ipmr_vif_entry_notifier(struct notifier_block *nb,
> +					struct net *net,
> +					enum fib_event_type event_type,
> +					struct vif_device *vif,
> +					vifi_t vif_index, u32 tb_id)
> +{
> +	struct vif_entry_notifier_info info = {
> +		.info = {
> +			.family = RTNL_FAMILY_IPMR,
> +			.net = net,
> +		},
> +		.dev = vif->dev,
> +		.vif_index = vif_index,
> +		.vif_flags = vif->flags,
> +		.tb_id = tb_id,
> +	};

We only use info.info which is fib_notifier_info, the
vif_entry_notifier_info seems to be not needed, why not just
use fib_notifier_info?

> +
> +	return call_fib_notifier(nb, net, event_type, &info.info);
> +}
> +
> +static int call_ipmr_mfc_entry_notifier(struct notifier_block *nb,
> +					struct net *net,
> +					enum fib_event_type event_type,
> +					struct mfc_cache *mfc, u32 tb_id)
> +{
> +	struct mfc_entry_notifier_info info = {
> +		.info = {
> +			.family = RTNL_FAMILY_IPMR,
> +			.net = net,
> +		},
> +		.mfc = mfc,
> +		.tb_id = tb_id
> +	};
> +

As above.

> +	return call_fib_notifier(nb, net, event_type, &info.info);
> +}
> +
>  /**
>   *	vif_delete - Delete a VIF entry
>   *	@notify: Set to 1, if the caller is a notifier_call
> @@ -3050,14 +3107,87 @@ static const struct net_protocol pim_protocol = {
>  };
>  #endif
>  
> +static unsigned int ipmr_seq_read(struct net *net)
> +{
> +	ASSERT_RTNL();
> +
> +	return net->ipv4.ipmr_seq + ipmr_rules_seq_read(net);
> +}
> +
> +static int ipmr_dump(struct net *net, struct notifier_block *nb)
> +{
> +	struct mr_table *mrt;
> +	int err;
> +
> +	err = ipmr_rules_dump(net, nb);
> +	if (err)
> +		return err;
> +
> +	ipmr_for_each_table(mrt, net) {
> +		struct vif_device *v = &mrt->vif_table[0];
> +		struct mfc_cache *mfc;
> +		int vifi;
> +
> +		/* Notifiy on table VIF entries */
> +		read_lock(&mrt_lock);
> +		for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) {
> +			if (!v->dev)
> +				continue;
> +
> +			call_ipmr_vif_entry_notifier(nb, net, FIB_EVENT_VIF_ADD,
> +						     v, vifi, mrt->id);
> +		}
> +		read_unlock(&mrt_lock);
> +
> +		/* Notify on table MFC entries */
> +		list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list)
> +			call_ipmr_mfc_entry_notifier(nb, net,
> +						     FIB_EVENT_ENTRY_ADD, mfc,
> +						     mrt->id);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct fib_notifier_ops ipmr_notifier_ops_template = {
> +	.family		= RTNL_FAMILY_IPMR,
> +	.fib_seq_read	= ipmr_seq_read,
> +	.fib_dump	= ipmr_dump,
> +	.owner		= THIS_MODULE,
> +};
> +
> +int __net_init ipmr_notifier_init(struct net *net)
> +{
> +	struct fib_notifier_ops *ops;
> +
> +	net->ipv4.ipmr_seq = 0;
> +
> +	ops = fib_notifier_ops_register(&ipmr_notifier_ops_template, net);
> +	if (IS_ERR(ops))
> +		return PTR_ERR(ops);
> +	net->ipv4.ipmr_notifier_ops = ops;
> +
> +	return 0;
> +}
> +
> +static void __net_exit ipmr_notifier_exit(struct net *net)
> +{
> +	fib_notifier_ops_unregister(net->ipv4.ipmr_notifier_ops);
> +	net->ipv4.ipmr_notifier_ops = NULL;
> +}
> +
>  /* Setup for IP multicast routing */
>  static int __net_init ipmr_net_init(struct net *net)
>  {
>  	int err;
>  
> +	err = ipmr_notifier_init(net);
> +	if (err)
> +		goto ipmr_notifier_fail;
> +
>  	err = ipmr_rules_init(net);
>  	if (err < 0)
> -		goto fail;
> +		goto ipmr_rules_fail;
>  
>  #ifdef CONFIG_PROC_FS
>  	err = -ENOMEM;
> @@ -3074,7 +3204,9 @@ static int __net_init ipmr_net_init(struct net *net)
>  proc_vif_fail:
>  	ipmr_rules_exit(net);
>  #endif
> -fail:
> +ipmr_rules_fail:
> +	ipmr_notifier_exit(net);
> +ipmr_notifier_fail:
>  	return err;
>  }
>  
> @@ -3084,6 +3216,7 @@ static void __net_exit ipmr_net_exit(struct net *net)
>  	remove_proc_entry("ip_mr_cache", net->proc_net);
>  	remove_proc_entry("ip_mr_vif", net->proc_net);
>  #endif
> +	ipmr_notifier_exit(net);
>  	ipmr_rules_exit(net);
>  }
>  
> 

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