Re: [PATCH 2/2] IPVS netns shutdown/startup dead-lock (Take III)

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	Hello,

On Tue, 4 Oct 2011, Hans Schillstrom wrote:

> From: Hans Schillstrom <hans@xxxxxxxxxxxxxxx>
> 
> ip_vs_mutext is used by both netns shutdown code and startup
> and both implicit uses sk_lock-AF_INET mutex.
> 
> cleanup CPU-1         startup CPU-2
> ip_vs_dst_event()     ip_vs_genl_set_cmd()
>  sk_lock-AF_INET     __ip_vs_mutex
>                      sk_lock-AF_INET
> __ip_vs_mutex
> * DEAD LOCK *
> 
> A new mutex placed in ip_vs netns struct called sync_mutex is added.
> 
> Comments from Julian and Simon added.
> This patch has been running for more than 3 month now and it seems to work.
> 
> Ver. 3
>     IP_VS_SO_GET_DAEMON in do_ip_vs_get_ctl protected by sync_mutex
>     instead of __ip_vs_mutex as sugested by Julian.
> 
> Signed-off-by: Hans Schillstrom <hans@xxxxxxxxxxxxxxx>

	Looks good to me, with one extra empty line in
start_sync_thread

Acked-by: Julian Anastasov <ja@xxxxxx>

> ---
>  include/net/ip_vs.h             |    1 +
>  net/netfilter/ipvs/ip_vs_ctl.c  |  131 ++++++++++++++++++++++++---------------
>  net/netfilter/ipvs/ip_vs_sync.c |    6 ++
>  3 files changed, 87 insertions(+), 51 deletions(-)
> 
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index 1aaf915..8fa4430 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -900,6 +900,7 @@ struct netns_ipvs {
>  	volatile int		sync_state;
>  	volatile int		master_syncid;
>  	volatile int		backup_syncid;
> +	struct mutex		sync_mutex;
>  	/* multicast interface name */
>  	char			master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
>  	char			backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index a1af72f..c77b5a0 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -2284,6 +2284,7 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
>  	struct ip_vs_service *svc;
>  	struct ip_vs_dest_user *udest_compat;
>  	struct ip_vs_dest_user_kern udest;
> +	struct netns_ipvs *ipvs = net_ipvs(net);
>  
>  	if (!capable(CAP_NET_ADMIN))
>  		return -EPERM;
> @@ -2304,6 +2305,24 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
>  	/* increase the module use count */
>  	ip_vs_use_count_inc();
>  
> +	/* Handle daemons since they have another lock */
> +	if (cmd == IP_VS_SO_SET_STARTDAEMON ||
> +	    cmd == IP_VS_SO_SET_STOPDAEMON) {
> +		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
> +
> +		if (mutex_lock_interruptible(&ipvs->sync_mutex)) {
> +			ret = -ERESTARTSYS;
> +			goto out_dec;
> +		}
> +		if (cmd == IP_VS_SO_SET_STARTDAEMON)
> +			ret = start_sync_thread(net, dm->state, dm->mcast_ifn,
> +						dm->syncid);
> +		else
> +			ret = stop_sync_thread(net, dm->state);
> +		mutex_unlock(&ipvs->sync_mutex);
> +		goto out_dec;
> +	}
> +
>  	if (mutex_lock_interruptible(&__ip_vs_mutex)) {
>  		ret = -ERESTARTSYS;
>  		goto out_dec;
> @@ -2317,15 +2336,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
>  		/* Set timeout values for (tcp tcpfin udp) */
>  		ret = ip_vs_set_timeout(net, (struct ip_vs_timeout_user *)arg);
>  		goto out_unlock;
> -	} else if (cmd == IP_VS_SO_SET_STARTDAEMON) {
> -		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
> -		ret = start_sync_thread(net, dm->state, dm->mcast_ifn,
> -					dm->syncid);
> -		goto out_unlock;
> -	} else if (cmd == IP_VS_SO_SET_STOPDAEMON) {
> -		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
> -		ret = stop_sync_thread(net, dm->state);
> -		goto out_unlock;
>  	}
>  
>  	usvc_compat = (struct ip_vs_service_user *)arg;
> @@ -2585,6 +2595,33 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>  
>  	if (copy_from_user(arg, user, copylen) != 0)
>  		return -EFAULT;
> +	/*
> +	 * Handle daemons first since it has its own locking
> +	 */
> +	if (cmd == IP_VS_SO_GET_DAEMON) {
> +		struct ip_vs_daemon_user d[2];
> +
> +		memset(&d, 0, sizeof(d));
> +		if (mutex_lock_interruptible(&ipvs->sync_mutex))
> +			return -ERESTARTSYS;
> +
> +		if (ipvs->sync_state & IP_VS_STATE_MASTER) {
> +			d[0].state = IP_VS_STATE_MASTER;
> +			strlcpy(d[0].mcast_ifn, ipvs->master_mcast_ifn,
> +				sizeof(d[0].mcast_ifn));
> +			d[0].syncid = ipvs->master_syncid;
> +		}
> +		if (ipvs->sync_state & IP_VS_STATE_BACKUP) {
> +			d[1].state = IP_VS_STATE_BACKUP;
> +			strlcpy(d[1].mcast_ifn, ipvs->backup_mcast_ifn,
> +				sizeof(d[1].mcast_ifn));
> +			d[1].syncid = ipvs->backup_syncid;
> +		}
> +		if (copy_to_user(user, &d, sizeof(d)) != 0)
> +			ret = -EFAULT;
> +		mutex_unlock(&ipvs->sync_mutex);
> +		return ret;
> +	}
>  
>  	if (mutex_lock_interruptible(&__ip_vs_mutex))
>  		return -ERESTARTSYS;
> @@ -2682,28 +2719,6 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>  	}
>  	break;
>  
> -	case IP_VS_SO_GET_DAEMON:
> -	{
> -		struct ip_vs_daemon_user d[2];
> -
> -		memset(&d, 0, sizeof(d));
> -		if (ipvs->sync_state & IP_VS_STATE_MASTER) {
> -			d[0].state = IP_VS_STATE_MASTER;
> -			strlcpy(d[0].mcast_ifn, ipvs->master_mcast_ifn,
> -				sizeof(d[0].mcast_ifn));
> -			d[0].syncid = ipvs->master_syncid;
> -		}
> -		if (ipvs->sync_state & IP_VS_STATE_BACKUP) {
> -			d[1].state = IP_VS_STATE_BACKUP;
> -			strlcpy(d[1].mcast_ifn, ipvs->backup_mcast_ifn,
> -				sizeof(d[1].mcast_ifn));
> -			d[1].syncid = ipvs->backup_syncid;
> -		}
> -		if (copy_to_user(user, &d, sizeof(d)) != 0)
> -			ret = -EFAULT;
> -	}
> -	break;
> -
>  	default:
>  		ret = -EINVAL;
>  	}
> @@ -3206,7 +3221,7 @@ static int ip_vs_genl_dump_daemons(struct sk_buff *skb,
>  	struct net *net = skb_sknet(skb);
>  	struct netns_ipvs *ipvs = net_ipvs(net);
>  
> -	mutex_lock(&__ip_vs_mutex);
> +	mutex_lock(&ipvs->sync_mutex);
>  	if ((ipvs->sync_state & IP_VS_STATE_MASTER) && !cb->args[0]) {
>  		if (ip_vs_genl_dump_daemon(skb, IP_VS_STATE_MASTER,
>  					   ipvs->master_mcast_ifn,
> @@ -3226,7 +3241,7 @@ static int ip_vs_genl_dump_daemons(struct sk_buff *skb,
>  	}
>  
>  nla_put_failure:
> -	mutex_unlock(&__ip_vs_mutex);
> +	mutex_unlock(&ipvs->sync_mutex);
>  
>  	return skb->len;
>  }
> @@ -3272,13 +3287,9 @@ static int ip_vs_genl_set_config(struct net *net, struct nlattr **attrs)
>  	return ip_vs_set_timeout(net, &t);
>  }
>  
> -static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info)
> +static int ip_vs_genl_set_daemon(struct sk_buff *skb, struct genl_info *info)
>  {
> -	struct ip_vs_service *svc = NULL;
> -	struct ip_vs_service_user_kern usvc;
> -	struct ip_vs_dest_user_kern udest;
>  	int ret = 0, cmd;
> -	int need_full_svc = 0, need_full_dest = 0;
>  	struct net *net;
>  	struct netns_ipvs *ipvs;
>  
> @@ -3286,19 +3297,10 @@ static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info)
>  	ipvs = net_ipvs(net);
>  	cmd = info->genlhdr->cmd;
>  
> -	mutex_lock(&__ip_vs_mutex);
> -
> -	if (cmd == IPVS_CMD_FLUSH) {
> -		ret = ip_vs_flush(net);
> -		goto out;
> -	} else if (cmd == IPVS_CMD_SET_CONFIG) {
> -		ret = ip_vs_genl_set_config(net, info->attrs);
> -		goto out;
> -	} else if (cmd == IPVS_CMD_NEW_DAEMON ||
> -		   cmd == IPVS_CMD_DEL_DAEMON) {
> -
> +	if (cmd == IPVS_CMD_NEW_DAEMON || cmd == IPVS_CMD_DEL_DAEMON) {
>  		struct nlattr *daemon_attrs[IPVS_DAEMON_ATTR_MAX + 1];
>  
> +		mutex_lock(&ipvs->sync_mutex);
>  		if (!info->attrs[IPVS_CMD_ATTR_DAEMON] ||
>  		    nla_parse_nested(daemon_attrs, IPVS_DAEMON_ATTR_MAX,
>  				     info->attrs[IPVS_CMD_ATTR_DAEMON],
> @@ -3311,6 +3313,33 @@ static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info)
>  			ret = ip_vs_genl_new_daemon(net, daemon_attrs);
>  		else
>  			ret = ip_vs_genl_del_daemon(net, daemon_attrs);
> +out:
> +		mutex_unlock(&ipvs->sync_mutex);
> +	}
> +	return ret;
> +}
> +
> +static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info)
> +{
> +	struct ip_vs_service *svc = NULL;
> +	struct ip_vs_service_user_kern usvc;
> +	struct ip_vs_dest_user_kern udest;
> +	int ret = 0, cmd;
> +	int need_full_svc = 0, need_full_dest = 0;
> +	struct net *net;
> +	struct netns_ipvs *ipvs;
> +
> +	net = skb_sknet(skb);
> +	ipvs = net_ipvs(net);
> +	cmd = info->genlhdr->cmd;
> +
> +	mutex_lock(&__ip_vs_mutex);
> +
> +	if (cmd == IPVS_CMD_FLUSH) {
> +		ret = ip_vs_flush(net);
> +		goto out;
> +	} else if (cmd == IPVS_CMD_SET_CONFIG) {
> +		ret = ip_vs_genl_set_config(net, info->attrs);
>  		goto out;
>  	} else if (cmd == IPVS_CMD_ZERO &&
>  		   !info->attrs[IPVS_CMD_ATTR_SERVICE]) {
> @@ -3537,13 +3566,13 @@ static struct genl_ops ip_vs_genl_ops[] __read_mostly = {
>  		.cmd	= IPVS_CMD_NEW_DAEMON,
>  		.flags	= GENL_ADMIN_PERM,
>  		.policy	= ip_vs_cmd_policy,
> -		.doit	= ip_vs_genl_set_cmd,
> +		.doit	= ip_vs_genl_set_daemon,
>  	},
>  	{
>  		.cmd	= IPVS_CMD_DEL_DAEMON,
>  		.flags	= GENL_ADMIN_PERM,
>  		.policy	= ip_vs_cmd_policy,
> -		.doit	= ip_vs_genl_set_cmd,
> +		.doit	= ip_vs_genl_set_daemon,
>  	},
>  	{
>  		.cmd	= IPVS_CMD_GET_DAEMON,
> diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
> index 7ee7215..3cdd479 100644
> --- a/net/netfilter/ipvs/ip_vs_sync.c
> +++ b/net/netfilter/ipvs/ip_vs_sync.c
> @@ -61,6 +61,7 @@
>  
>  #define SYNC_PROTO_VER  1		/* Protocol version in header */
>  
> +static struct lock_class_key __ipvs_sync_key;
>  /*
>   *	IPVS sync connection entry
>   *	Version 0, i.e. original version.
> @@ -1545,6 +1546,7 @@ int start_sync_thread(struct net *net, int state, char *mcast_ifn, __u8 syncid)
>  	IP_VS_DBG(7, "Each ip_vs_sync_conn entry needs %Zd bytes\n",
>  		  sizeof(struct ip_vs_sync_conn_v0));
>  
> +
>  	if (state == IP_VS_STATE_MASTER) {
>  		if (ipvs->master_thread)
>  			return -EEXIST;
> @@ -1667,6 +1669,7 @@ int __net_init ip_vs_sync_net_init(struct net *net)
>  {
>  	struct netns_ipvs *ipvs = net_ipvs(net);
>  
> +	__mutex_init(&ipvs->sync_mutex, "ipvs->sync_mutex", &__ipvs_sync_key);
>  	INIT_LIST_HEAD(&ipvs->sync_queue);
>  	spin_lock_init(&ipvs->sync_lock);
>  	spin_lock_init(&ipvs->sync_buff_lock);
> @@ -1680,7 +1683,9 @@ int __net_init ip_vs_sync_net_init(struct net *net)
>  void ip_vs_sync_net_cleanup(struct net *net)
>  {
>  	int retc;
> +	struct netns_ipvs *ipvs = net_ipvs(net);
>  
> +	mutex_lock(&ipvs->sync_mutex);
>  	retc = stop_sync_thread(net, IP_VS_STATE_MASTER);
>  	if (retc && retc != -ESRCH)
>  		pr_err("Failed to stop Master Daemon\n");
> @@ -1688,4 +1693,5 @@ void ip_vs_sync_net_cleanup(struct net *net)
>  	retc = stop_sync_thread(net, IP_VS_STATE_BACKUP);
>  	if (retc && retc != -ESRCH)
>  		pr_err("Failed to stop Backup Daemon\n");
> +	mutex_unlock(&ipvs->sync_mutex);
>  }
> -- 
> 1.7.4.4

Regards

--
Julian Anastasov <ja@xxxxxx>
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