[RFC PATCH v2 38/45] mptcp: implement memory accounting for mptcp rtx queue

[Mat Martineau]

From: Paolo Abeni <pab...@redhat.com>

Charge the data on the rtx queue to the master MPTCP socket, too.
Such memory in uncharged when the data is acked/dequeued.

Also account mptcp sockets inuse via a protocol specific pcpu
counter.

Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
 net/mptcp/protocol.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 1f7a090ed25c..8319ee807481 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -19,6 +19,8 @@
 #include <net/mptcp.h>
 #include "protocol.h"
 
+static struct percpu_counter mptcp_sockets_allocated;
+
 static void mptcp_set_timeout(const struct sock *sk, const struct sock *ssk)
 {
        unsigned long tout = ssk && inet_csk(ssk)->icsk_pending ?
@@ -112,9 +114,10 @@ static inline bool mptcp_frag_can_collapse_to(const struct 
mptcp_sock *msk,
                df->data_seq + df->data_len == msk->write_seq;
 }
 
-static void dfrag_clear(struct mptcp_data_frag *dfrag)
+static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag)
 {
        list_del(&dfrag->list);
+       sk_mem_uncharge(sk, dfrag->data_len + dfrag->overhead);
        put_page(dfrag->page);
 }
 
@@ -128,8 +131,9 @@ static void mptcp_clean_una(struct sock *sk)
                if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
                        break;
 
-               dfrag_clear(dfrag);
+               dfrag_clear(sk, dfrag);
        }
+       sk_mem_reclaim_partial(sk);
 }
 
 /* ensure we get enough memory for the frag hdr, beyond some minimal amount of
@@ -236,6 +240,9 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock 
*ssk,
        if (!psize)
                return -EINVAL;
 
+       if (!sk_wmem_schedule(sk, psize + dfrag->overhead))
+               return -ENOMEM;
+
        /* tell the TCP stack to delay the push so that we can safely
         * access the skb after the sendpages call
         */
@@ -257,6 +264,11 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock 
*ssk,
                list_add_tail(&dfrag->list, &msk->rtx_queue);
        }
 
+       /* charge data on mptcp rtx queue to the master socket
+        * Note: we charge such data both to sk and ssk
+        */
+       sk->sk_forward_alloc -= frag_truesize;
+
        collapsed = skb == tcp_write_queue_tail(ssk);
        if (collapsed) {
                WARN_ON_ONCE(!can_collapse);
@@ -769,6 +781,8 @@ static int mptcp_init_sock(struct sock *sk)
        if (ret)
                return ret;
 
+       sk_sockets_allocated_inc(sk);
+
        if (!mptcp_is_enabled(sock_net(sk)))
                return -ENOPROTOOPT;
 
@@ -783,7 +797,7 @@ static void __mptcp_clear_xmit(struct sock *sk)
        sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer);
 
        list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list)
-               dfrag_clear(dfrag);
+               dfrag_clear(sk, dfrag);
 }
 
 static void mptcp_close(struct sock *sk, long timeout)
@@ -902,6 +916,7 @@ static struct sock *mptcp_accept(struct sock *sk, int 
flags, int *err,
 
 static void mptcp_destroy(struct sock *sk)
 {
+       sk_sockets_allocated_dec(sk);
 }
 
 static int mptcp_setsockopt(struct sock *sk, int level, int optname,
@@ -1088,6 +1103,11 @@ static struct proto mptcp_prot = {
        .hash           = inet_hash,
        .unhash         = inet_unhash,
        .get_port       = mptcp_get_port,
+       .sockets_allocated      = &mptcp_sockets_allocated,
+       .memory_allocated       = &tcp_memory_allocated,
+       .memory_pressure        = &tcp_memory_pressure,
+       .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_wmem),
+       .sysctl_mem     = sysctl_tcp_mem,
        .obj_size       = sizeof(struct mptcp_sock),
        .no_autobind    = 1,
 };
@@ -1324,6 +1344,9 @@ void mptcp_proto_init(void)
        mptcp_stream_ops.listen = mptcp_listen;
        mptcp_stream_ops.shutdown = mptcp_shutdown;
 
+       if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL))
+               panic("Failed to allocate MPTCP pcpu counter\n");
+
        mptcp_subflow_init();
        pm_init();
 
-- 
2.23.0