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Date:   Thu, 30 Jul 2020 16:39:04 +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: <20200730143904.liappabxaretvah6@wittgenstein>
References: <159611007271.535980.15362304262237658692.stgit@localhost.localdomain>
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 <20200730143049.m3isrpwrktxnh7pz@wittgenstein>
 <2f922e05-fd2b-f176-727a-f8b913087891@virtuozzo.com>
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On Thu, Jul 30, 2020 at 05:34:28PM +0300, Kirill Tkhai wrote:
> On 30.07.2020 17:30, Christian Brauner wrote:
> > 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>
> >> ---
> >>  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;
> > 
> > Hm, I wonder whether it's worth to have this addition be in a separate
> > patch but probably not and even if there'd be no need to resend.
> > 
> > Though I wonder, isn't this missing an include for refcount_t or is
> > there some header-magic we're doing during pre-processing?
> 
> We have to add, I think. I'll resend with #include <linux/refcount.h>
> in this file. Can I keep your Ack here on resend?

Sure.

>  
> > Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
> > 
> > Thanks!
> > Christian
> > 
> >>  };
> >>  
> >>  #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);
> >>
> >>
>