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Date:   Thu, 30 Jul 2020 15:35:26 +0200
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Kirill Tkhai <ktkhai@virtuozzo.com>
Cc:     viro@zeniv.linux.org.uk, adobriyan@gmail.com, davem@davemloft.net,
        ebiederm@xmission.com, akpm@linux-foundation.org,
        areber@redhat.com, serge@hallyn.com, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 01/23] ns: Add common refcount into ns_common add use it
 as counter for net_ns
Message-ID: <20200730133526.4lhkmlamgxjdssip@wittgenstein>
References: <159611007271.535980.15362304262237658692.stgit@localhost.localdomain>
 <159611036589.535980.1765795847221907147.stgit@localhost.localdomain>
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On Thu, Jul 30, 2020 at 02:59:25PM +0300, Kirill Tkhai wrote:
> Currently, every type of namespaces has its own counter,
> which is stored in ns-specific part. Say, @net has
> struct net::count, @pid has struct pid_namespace::kref, etc.
> 
> This patchset introduces unified counter for all types
> of namespaces, and converts net namespace to use it first.
> 
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> ---

Any reason the refcount changes need to be tied to the procfs changes?
Seems that should be a separate cleanup patchset which we can take
independent of procfs changes.

Thanks!
Christian

>  include/linux/ns_common.h     |    1 +
>  include/net/net_namespace.h   |   11 ++++-------
>  net/core/net-sysfs.c          |    6 +++---
>  net/core/net_namespace.c      |    6 +++---
>  net/ipv4/inet_timewait_sock.c |    4 ++--
>  net/ipv4/tcp_metrics.c        |    2 +-
>  6 files changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
> index 5fbc4000358f..27db02ebdf36 100644
> --- a/include/linux/ns_common.h
> +++ b/include/linux/ns_common.h
> @@ -8,6 +8,7 @@ struct ns_common {
>  	atomic_long_t stashed;
>  	const struct proc_ns_operations *ops;
>  	unsigned int inum;
> +	refcount_t count;
>  };
>  
>  #endif
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index 2ee5901bec7a..cb4b33d7834b 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -60,9 +60,6 @@ struct net {
>  	refcount_t		passive;	/* To decide when the network
>  						 * namespace should be freed.
>  						 */
> -	refcount_t		count;		/* To decided when the network
> -						 *  namespace should be shut down.
> -						 */
>  	spinlock_t		rules_mod_lock;
>  
>  	unsigned int		dev_unreg_count;
> @@ -245,7 +242,7 @@ void __put_net(struct net *net);
>  
>  static inline struct net *get_net(struct net *net)
>  {
> -	refcount_inc(&net->count);
> +	refcount_inc(&net->ns.count);
>  	return net;
>  }
>  
> @@ -256,14 +253,14 @@ static inline struct net *maybe_get_net(struct net *net)
>  	 * exists.  If the reference count is zero this
>  	 * function fails and returns NULL.
>  	 */
> -	if (!refcount_inc_not_zero(&net->count))
> +	if (!refcount_inc_not_zero(&net->ns.count))
>  		net = NULL;
>  	return net;
>  }
>  
>  static inline void put_net(struct net *net)
>  {
> -	if (refcount_dec_and_test(&net->count))
> +	if (refcount_dec_and_test(&net->ns.count))
>  		__put_net(net);
>  }
>  
> @@ -275,7 +272,7 @@ int net_eq(const struct net *net1, const struct net *net2)
>  
>  static inline int check_net(const struct net *net)
>  {
> -	return refcount_read(&net->count) != 0;
> +	return refcount_read(&net->ns.count) != 0;
>  }
>  
>  void net_drop_ns(void *);
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 9de33b594ff2..655a88b0071c 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1025,7 +1025,7 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
>  	while (--i >= new_num) {
>  		struct kobject *kobj = &dev->_rx[i].kobj;
>  
> -		if (!refcount_read(&dev_net(dev)->count))
> +		if (!refcount_read(&dev_net(dev)->ns.count))
>  			kobj->uevent_suppress = 1;
>  		if (dev->sysfs_rx_queue_group)
>  			sysfs_remove_group(kobj, dev->sysfs_rx_queue_group);
> @@ -1603,7 +1603,7 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
>  	while (--i >= new_num) {
>  		struct netdev_queue *queue = dev->_tx + i;
>  
> -		if (!refcount_read(&dev_net(dev)->count))
> +		if (!refcount_read(&dev_net(dev)->ns.count))
>  			queue->kobj.uevent_suppress = 1;
>  #ifdef CONFIG_BQL
>  		sysfs_remove_group(&queue->kobj, &dql_group);
> @@ -1850,7 +1850,7 @@ void netdev_unregister_kobject(struct net_device *ndev)
>  {
>  	struct device *dev = &ndev->dev;
>  
> -	if (!refcount_read(&dev_net(ndev)->count))
> +	if (!refcount_read(&dev_net(ndev)->ns.count))
>  		dev_set_uevent_suppress(dev, 1);
>  
>  	kobject_get(&dev->kobj);
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index dcd61aca343e..5f658cbedd34 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -44,7 +44,7 @@ static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
>  #endif
>  
>  struct net init_net = {
> -	.count		= REFCOUNT_INIT(1),
> +	.ns.count	= REFCOUNT_INIT(1),
>  	.dev_base_head	= LIST_HEAD_INIT(init_net.dev_base_head),
>  #ifdef CONFIG_KEYS
>  	.key_domain	= &init_net_key_domain,
> @@ -248,7 +248,7 @@ int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
>  {
>  	int id;
>  
> -	if (refcount_read(&net->count) == 0)
> +	if (refcount_read(&net->ns.count) == 0)
>  		return NETNSA_NSID_NOT_ASSIGNED;
>  
>  	spin_lock(&net->nsid_lock);
> @@ -328,7 +328,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
>  	int error = 0;
>  	LIST_HEAD(net_exit_list);
>  
> -	refcount_set(&net->count, 1);
> +	refcount_set(&net->ns.count, 1);
>  	refcount_set(&net->passive, 1);
>  	get_random_bytes(&net->hash_mix, sizeof(u32));
>  	net->dev_base_seq = 1;
> diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
> index c411c87ae865..437afe392e66 100644
> --- a/net/ipv4/inet_timewait_sock.c
> +++ b/net/ipv4/inet_timewait_sock.c
> @@ -272,14 +272,14 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
>  				continue;
>  			tw = inet_twsk(sk);
>  			if ((tw->tw_family != family) ||
> -				refcount_read(&twsk_net(tw)->count))
> +				refcount_read(&twsk_net(tw)->ns.count))
>  				continue;
>  
>  			if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt)))
>  				continue;
>  
>  			if (unlikely((tw->tw_family != family) ||
> -				     refcount_read(&twsk_net(tw)->count))) {
> +				     refcount_read(&twsk_net(tw)->ns.count))) {
>  				inet_twsk_put(tw);
>  				goto restart;
>  			}
> diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
> index 279db8822439..39710c417565 100644
> --- a/net/ipv4/tcp_metrics.c
> +++ b/net/ipv4/tcp_metrics.c
> @@ -887,7 +887,7 @@ static void tcp_metrics_flush_all(struct net *net)
>  		pp = &hb->chain;
>  		for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
>  			match = net ? net_eq(tm_net(tm), net) :
> -				!refcount_read(&tm_net(tm)->count);
> +				!refcount_read(&tm_net(tm)->ns.count);
>  			if (match) {
>  				*pp = tm->tcpm_next;
>  				kfree_rcu(tm, rcu_head);
> 
>