Hi,

this is the third version of the patchset introducing net_sem
instead of net_mutex. The patchset adds net_sem in addition
to net_mutex and allows pernet_operations to be "async". This
flag means, the pernet_operations methods are safe to be
executed with any other pernet_operations (un)initializing
another net.

If there are only async pernet_operations in the system,
net_mutex is not used either for setup_net() or for cleanup_net().

The pernet_operations converted in this patchset allow
to create minimal .config to have network working, and
the changes improve the performance like you may see
below:

    %for i in {1..10000}; do unshare -n bash -c exit; done
    
    *before*
    real 1m40,377s
    user 0m9,672s
    sys 0m19,928s
    
    *after*
    real 0m17,007s
    user 0m5,311s
    sys 0m11,779
    
    (5.8 times faster)

In the future, when all pernet_operations become async,
we'll just remove this "async" field tree-wide.

All the new logic is concentrated in patches [1-5/32].
The rest of patches converts specific operations:
review, rationale of they can be converted, and setting
of async flag.

Kirill

v3: Improved patches descriptions. Added comment into [5/32].
Added [32/32] converting netlink_tap_net_ops (new pernet operations
introduced in 2018).

v2: Single patch -> patchset with rationale of every conversion

---

Kirill Tkhai (32):
      net: Assign net to net_namespace_list in setup_net()
      net: Cleanup in copy_net_ns()
      net: Introduce net_sem for protection of pernet_list
      net: Move mutex_unlock() in cleanup_net() up
      net: Allow pernet_operations to be executed in parallel
      net: Convert proc_net_ns_ops
      net: Convert net_ns_ops methods
      net: Convert sysctl_pernet_ops
      net: Convert netfilter_net_ops
      net: Convert nf_log_net_ops
      net: Convert net_inuse_ops
      net: Convert net_defaults_ops
      net: Convert netlink_net_ops
      net: Convert rtnetlink_net_ops
      net: Convert audit_net_ops
      net: Convert uevent_net_ops
      net: Convert proto_net_ops
      net: Convert pernet_subsys ops, registered via net_dev_init()
      net: Convert fib_* pernet_operations, registered via subsys_initcall
      net: Convert subsys_initcall() registered pernet_operations from net/sched
      net: Convert genl_pernet_ops
      net: Convert wext_pernet_ops
      net: Convert sysctl_core_ops
      net: Convert pernet_subsys, registered from inet_init()
      net: Convert unix_net_ops
      net: Convert packet_net_ops
      net: Convert ipv4_sysctl_ops
      net: Convert addrconf_ops
      net: Convert loopback_net_ops
      net: Convert default_device_ops
      net: Convert diag_net_ops
      net: Convert netlink_tap_net_ops


 drivers/net/loopback.c      |    1 
 fs/proc/proc_net.c          |    1 
 include/linux/rtnetlink.h   |    1 
 include/net/net_namespace.h |    6 +++
 kernel/audit.c              |    1 
 lib/kobject_uevent.c        |    1 
 net/core/dev.c              |    2 +
 net/core/fib_notifier.c     |    1 
 net/core/fib_rules.c        |    1 
 net/core/net-procfs.c       |    2 +
 net/core/net_namespace.c    |   95 +++++++++++++++++++++++++------------------
 net/core/rtnetlink.c        |    5 +-
 net/core/sock.c             |    2 +
 net/core/sock_diag.c        |    1 
 net/core/sysctl_net_core.c  |    1 
 net/ipv4/af_inet.c          |    2 +
 net/ipv4/arp.c              |    1 
 net/ipv4/devinet.c          |    1 
 net/ipv4/fib_frontend.c     |    1 
 net/ipv4/icmp.c             |    1 
 net/ipv4/igmp.c             |    1 
 net/ipv4/ip_fragment.c      |    1 
 net/ipv4/ipmr.c             |    1 
 net/ipv4/ping.c             |    1 
 net/ipv4/proc.c             |    1 
 net/ipv4/raw.c              |    1 
 net/ipv4/route.c            |    4 ++
 net/ipv4/sysctl_net_ipv4.c  |    1 
 net/ipv4/tcp_ipv4.c         |    2 +
 net/ipv4/tcp_metrics.c      |    1 
 net/ipv4/udp.c              |    1 
 net/ipv4/udplite.c          |    1 
 net/ipv4/xfrm4_policy.c     |    1 
 net/ipv6/addrconf.c         |    1 
 net/netfilter/core.c        |    1 
 net/netfilter/nf_log.c      |    1 
 net/netlink/af_netlink.c    |    2 +
 net/netlink/genetlink.c     |    1 
 net/packet/af_packet.c      |    1 
 net/sched/act_api.c         |    1 
 net/sched/sch_api.c         |    1 
 net/sysctl_net.c            |    1 
 net/unix/af_unix.c          |    1 
 net/wireless/wext-core.c    |    1 
 net/xfrm/xfrm_policy.c      |    1 
 45 files changed, 116 insertions(+), 41 deletions(-)

--
Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
Acked-by: Andrei Vagin <ava...@virtuozzo.com>

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