[Devel] [PATCH RHEL7 COMMIT] net: Cleanup in copy_net_ns()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1127.8.2.vz7.161.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.8.2.vz7.161.3
------>
commit 692368eb77ff13d9edcde4ca0c62bd7e74363c57
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Wed May 27 21:34:55 2020 +0300

    net: Cleanup in copy_net_ns()
    
    ms commit 5ba049a5cc8e
    
    Line up destructors actions in the revers order
    to constructors. Next patches will add more actions,
    and this will be comfortable, if there is the such
    order.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    Acked-by: Andrei Vagin <avagin at virtuozzo.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    
    =====================
    Patchset description:
    
    Parallel per-net init/exit
    
    https://jira.sw.ru/browse/PSBM-104158
---
 net/core/net_namespace.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 954f78c526d3d..c461acce68bb5 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -406,28 +406,35 @@ struct net *copy_net_ns(unsigned long flags,
 		return ERR_PTR(-ENOSPC);
 
 	if (atomic_dec_if_positive(&ve->netns_avail_nr) < 0) {
-		dec_net_namespaces(ucounts);
-		return ERR_PTR(-ENOMEM);
+		rv = -ENOMEM;
+		goto dec_ucounts;
+
 	}
 
 	net = net_alloc();
 	if (!net) {
-		dec_net_namespaces(ucounts);
-		atomic_inc(&ve->netns_avail_nr);
-		return ERR_PTR(-ENOMEM);
+		rv = -ENOMEM;
+		goto inc_avail_nr;
 	}
 
+	atomic_set(&net->passive, 1);
+	net->ucounts = ucounts;
 	get_user_ns(user_ns);
 
-	mutex_lock(&net_mutex);
-	net->ucounts = ucounts;
+	rv = mutex_lock_killable(&net_mutex);
+	if (rv < 0)
+		goto put_userns;
+
 	rv = setup_net(net, user_ns);
 	mutex_unlock(&net_mutex);
 	if (rv < 0) {
-		dec_net_namespaces(ucounts);
+put_userns:
 		put_user_ns(user_ns);
 		net_drop_ns(net);
+inc_avail_nr:
 		atomic_inc(&ve->netns_avail_nr);
+dec_ucounts:
+		dec_net_namespaces(ucounts);
 		return ERR_PTR(rv);
 	}
 	return net;