On 14.09.2018 23:32, Cong Wang wrote:
> ra_mutex is a IPv4 specific mutex, it is inside struct netns_ipv4,
> but its initialization is in the generic netns code, setup_net().
>
> Move it to IPv4 specific net init code, inet_init_net().
>
> Fixes: d9ff3049739e ("net: Replace ip_ra_lock with per-net mutex")
> Cc: Kirill Tkhai <ktk...@virtuozzo.com>
> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
> ---
> net/core/net_namespace.c | 1 -
> net/ipv4/af_inet.c | 2 ++
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index 670c84b1bfc2..b272ccfcbf63 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -308,7 +308,6 @@ static __net_init int setup_net(struct net *net, struct
> user_namespace *user_ns)
> net->user_ns = user_ns;
> idr_init(&net->netns_ids);
> spin_lock_init(&net->nsid_lock);
> - mutex_init(&net->ipv4.ra_mutex);
>
> list_for_each_entry(ops, &pernet_list, list) {
> error = ops_init(ops, net);
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 20fda8fb8ffd..57b7bffb93e5 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1817,6 +1817,8 @@ static __net_init int inet_init_net(struct net *net)
> net->ipv4.sysctl_igmp_llm_reports = 1;
> net->ipv4.sysctl_igmp_qrv = 2;
>
> + mutex_init(&net->ipv4.ra_mutex);
> +
In inet_init() the order of registration is:
ip_mr_init();
init_inet_pernet_ops();
This means, ipmr_net_ops pernet operations are before af_inet_ops
in pernet_list. So, there is a theoretical probability, sometimes
in the future, we will have a problem during a fail of net initialization.
Say,
setup_net():
ipmr_net_ops->init() returns 0
xxx->init() returns error
and then we do:
ipmr_net_ops->exit(),
which could touch ra_mutex (theoretically).
Your patch is OK, but since you do this, we may also swap the order
of registration of ipmr_net_ops and af_inet_ops better too.
Kirill
