Re: [PATCH v2 4/7] per-cgroup tcp buffers control

[Andrew Wagin]

* tcp_destroy_cgroup_fill() is executed for each cgroup and
initializes some proto methods. proto_list is global and we can
initialize each proto one time. Do we need this really?

* And when a cgroup is destroyed, it cleans proto methods
(tcp_destroy_cgroup_fill), how other cgroups will work after that?

* What about proto, which is registered when cgroup mounted?

My opinion that we may initialize proto by the following way:

+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM+       .enter_memory_pressure
= tcp_enter_memory_pressure_nocg,
+       .sockets_allocated      = sockets_allocated_tcp_nocg,
+       .memory_allocated       = memory_allocated_tcp_nocg,
+       .memory_pressure        = memory_pressure_tcp_nocg,
+#else
        .enter_memory_pressure  = tcp_enter_memory_pressure,
        .sockets_allocated      = sockets_allocated_tcp,
        .memory_allocated       = memory_allocated_tcp,
        .memory_pressure        = memory_pressure_tcp,
+#endif

It should work, because the root memory cgroup always exists.

>+int tcp_init_cgroup_fill(struct proto *prot, struct cgroup *cgrp,
>+                        struct cgroup_subsys *ss)
>+{
>+       prot->enter_memory_pressure     = tcp_enter_memory_pressure;
>+       prot->memory_allocated          = memory_allocated_tcp;
>+       prot->prot_mem                  = tcp_sysctl_mem;
>+       prot->sockets_allocated         = sockets_allocated_tcp;
>+       prot->memory_pressure           = memory_pressure_tcp;
>+
>+       return 0;
>+}


> +void tcp_destroy_cgroup_fill(struct proto *prot, struct cgroup *cgrp,
> +                            struct cgroup_subsys *ss)
> +{
> +       prot->enter_memory_pressure     = tcp_enter_memory_pressure_nocg;
> +       prot->memory_allocated          = memory_allocated_tcp_nocg;
> +       prot->prot_mem                  = tcp_sysctl_mem_nocg;
> +       prot->sockets_allocated         = sockets_allocated_tcp_nocg;
> +       prot->memory_pressure           = memory_pressure_tcp_nocg;
>

>@@ -2220,12 +2220,16 @@ struct proto tcpv6_prot = {
>       .hash                   = tcp_v6_hash,
>       .unhash                 = inet_unhash,
>       .get_port               = inet_csk_get_port
> +       .enter_memory_pressure  = tcp_enter_memory_pressure_nocg,
> +       .sockets_allocated      = sockets_allocated_tcp_nocg,
> +       .memory_allocated       = memory_allocated_tcp_nocg,
> +       .memory_pressure        = memory_pressure_tcp_nocg,
--
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