Display current tcp memory allocation in kmem cgroup

This patch introduces kmem.tcp.usage_in_bytes file, living in the
kmem_cgroup filesystem. It is a simple read-only file that displays the
amount of kernel memory currently consumed by the cgroup.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index e3533903409d..9481f235803e 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -17,6 +17,11 @@ static struct cftype tcp_files[] = {
                 .read_u64 = tcp_cgroup_read,
                 .private = RES_LIMIT,
         },
+        {
+                .name = "kmem.tcp.usage_in_bytes",
+                .read_u64 = tcp_cgroup_read,
+                .private = RES_USAGE,
+        },
 };
 
 static inline struct tcp_memcontrol *tcp_from_cgproto(struct cg_proto *cg_proto)
@@ -167,6 +172,19 @@ static u64 tcp_read_stat(struct mem_cgroup *memcg, int type, u64 default_val)
         return res_counter_read_u64(&tcp->tcp_memory_allocated, type);
 }
 
+static u64 tcp_read_usage(struct mem_cgroup *memcg)
+{
+        struct tcp_memcontrol *tcp;
+        struct cg_proto *cg_proto;
+
+        cg_proto = tcp_prot.proto_cgroup(memcg);
+        if (!cg_proto)
+                return atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT;
+
+        tcp = tcp_from_cgproto(cg_proto);
+        return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
+}
+
 static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
@@ -176,6 +194,9 @@ static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
         case RES_LIMIT:
                 val = tcp_read_stat(memcg, RES_LIMIT, RESOURCE_MAX);
                 break;
+        case RES_USAGE:
+                val = tcp_read_usage(memcg);
+                break;
         default:
                 BUG();
         }