From: Paolo Abeni pabeni@redhat.com
[ Upstream commit bc68b0efa1bf923cef1294a631d8e7416c7e06e4 ]
After commit c2e6048fa1cf ("mptcp: fix race in release_cb") we can move the whole MPTCP rx path under the socket lock leveraging the release_cb.
We can drop a bunch of spin_lock pairs in the receive functions, use a single receive queue and invoke __mptcp_move_skbs only when subflows ask for it.
This will allow more cleanup in the next patch.
Some changes are worth specific mention:
The msk rcvbuf update now always happens under both the msk and the subflow socket lock: we can drop a bunch of ONCE annotation and consolidate the checks.
When the skbs move is delayed at msk release callback time, even the msk rcvbuf update is delayed; additionally take care of such action in __mptcp_move_skbs().
Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20250218-net-next-mptcp-rx-path-refactor-v1-3-4a47d... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/mptcp/fastopen.c | 1 + net/mptcp/protocol.c | 123 ++++++++++++++++++++----------------------- net/mptcp/protocol.h | 2 +- 3 files changed, 60 insertions(+), 66 deletions(-)
diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index a29ff901df758..305f4c48ec158 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -49,6 +49,7 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subf MPTCP_SKB_CB(skb)->has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
mptcp_data_lock(sk); + DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk));
mptcp_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 42b239d9b2b3c..e4db98968e64d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -643,18 +643,6 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, bool more_data_avail; struct tcp_sock *tp; bool done = false; - int sk_rbuf; - - sk_rbuf = READ_ONCE(sk->sk_rcvbuf); - - if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) { - int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf); - - if (unlikely(ssk_rbuf > sk_rbuf)) { - WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf); - sk_rbuf = ssk_rbuf; - } - }
pr_debug("msk=%p ssk=%p\n", msk, ssk); tp = tcp_sk(ssk); @@ -722,7 +710,7 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, WRITE_ONCE(tp->copied_seq, seq); more_data_avail = mptcp_subflow_data_available(ssk);
- if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) { + if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) { done = true; break; } @@ -846,11 +834,30 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk) return moved > 0; }
+static void __mptcp_rcvbuf_update(struct sock *sk, struct sock *ssk) +{ + if (unlikely(ssk->sk_rcvbuf > sk->sk_rcvbuf)) + WRITE_ONCE(sk->sk_rcvbuf, ssk->sk_rcvbuf); +} + +static void __mptcp_data_ready(struct sock *sk, struct sock *ssk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + __mptcp_rcvbuf_update(sk, ssk); + + /* over limit? can't append more skbs to msk, Also, no need to wake-up*/ + if (__mptcp_rmem(sk) > sk->sk_rcvbuf) + return; + + /* Wake-up the reader only for in-sequence data */ + if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk)) + sk->sk_data_ready(sk); +} + void mptcp_data_ready(struct sock *sk, struct sock *ssk) { struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); - struct mptcp_sock *msk = mptcp_sk(sk); - int sk_rbuf, ssk_rbuf;
/* The peer can send data while we are shutting down this * subflow at msk destruction time, but we must avoid enqueuing @@ -859,19 +866,11 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk) if (unlikely(subflow->disposable)) return;
- ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf); - sk_rbuf = READ_ONCE(sk->sk_rcvbuf); - if (unlikely(ssk_rbuf > sk_rbuf)) - sk_rbuf = ssk_rbuf; - - /* over limit? can't append more skbs to msk, Also, no need to wake-up*/ - if (__mptcp_rmem(sk) > sk_rbuf) - return; - - /* Wake-up the reader only for in-sequence data */ mptcp_data_lock(sk); - if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk)) - sk->sk_data_ready(sk); + if (!sock_owned_by_user(sk)) + __mptcp_data_ready(sk, ssk); + else + __set_bit(MPTCP_DEQUEUE, &mptcp_sk(sk)->cb_flags); mptcp_data_unlock(sk); }
@@ -1944,16 +1943,17 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied);
-static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk, +static int __mptcp_recvmsg_mskq(struct sock *sk, struct msghdr *msg, size_t len, int flags, struct scm_timestamping_internal *tss, int *cmsg_flags) { + struct mptcp_sock *msk = mptcp_sk(sk); struct sk_buff *skb, *tmp; int copied = 0;
- skb_queue_walk_safe(&msk->receive_queue, skb, tmp) { + skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) { u32 offset = MPTCP_SKB_CB(skb)->offset; u32 data_len = skb->len - offset; u32 count = min_t(size_t, len - copied, data_len); @@ -1988,7 +1988,7 @@ static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk, /* we will bulk release the skb memory later */ skb->destructor = NULL; WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize); - __skb_unlink(skb, &msk->receive_queue); + __skb_unlink(skb, &sk->sk_receive_queue); __kfree_skb(skb); msk->bytes_consumed += count; } @@ -2113,54 +2113,46 @@ static void __mptcp_update_rmem(struct sock *sk) WRITE_ONCE(msk->rmem_released, 0); }
-static void __mptcp_splice_receive_queue(struct sock *sk) +static bool __mptcp_move_skbs(struct sock *sk) { + struct mptcp_subflow_context *subflow; struct mptcp_sock *msk = mptcp_sk(sk); - - skb_queue_splice_tail_init(&sk->sk_receive_queue, &msk->receive_queue); -} - -static bool __mptcp_move_skbs(struct mptcp_sock *msk) -{ - struct sock *sk = (struct sock *)msk; unsigned int moved = 0; bool ret, done;
+ /* verify we can move any data from the subflow, eventually updating */ + if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) + mptcp_for_each_subflow(msk, subflow) + __mptcp_rcvbuf_update(sk, subflow->tcp_sock); + + if (__mptcp_rmem(sk) > sk->sk_rcvbuf) + return false; + do { struct sock *ssk = mptcp_subflow_recv_lookup(msk); bool slowpath;
- /* we can have data pending in the subflows only if the msk - * receive buffer was full at subflow_data_ready() time, - * that is an unlikely slow path. - */ - if (likely(!ssk)) + if (unlikely(!ssk)) break;
slowpath = lock_sock_fast(ssk); - mptcp_data_lock(sk); __mptcp_update_rmem(sk); done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved); - mptcp_data_unlock(sk);
if (unlikely(ssk->sk_err)) __mptcp_error_report(sk); unlock_sock_fast(ssk, slowpath); } while (!done);
- /* acquire the data lock only if some input data is pending */ ret = moved > 0; if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) || - !skb_queue_empty_lockless(&sk->sk_receive_queue)) { - mptcp_data_lock(sk); + !skb_queue_empty(&sk->sk_receive_queue)) { __mptcp_update_rmem(sk); ret |= __mptcp_ofo_queue(msk); - __mptcp_splice_receive_queue(sk); - mptcp_data_unlock(sk); } if (ret) mptcp_check_data_fin((struct sock *)msk); - return !skb_queue_empty(&msk->receive_queue); + return ret; }
static unsigned int mptcp_inq_hint(const struct sock *sk) @@ -2168,7 +2160,7 @@ static unsigned int mptcp_inq_hint(const struct sock *sk) const struct mptcp_sock *msk = mptcp_sk(sk); const struct sk_buff *skb;
- skb = skb_peek(&msk->receive_queue); + skb = skb_peek(&sk->sk_receive_queue); if (skb) { u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
@@ -2214,7 +2206,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, while (copied < len) { int err, bytes_read;
- bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags, &tss, &cmsg_flags); + bytes_read = __mptcp_recvmsg_mskq(sk, msg, len - copied, flags, &tss, &cmsg_flags); if (unlikely(bytes_read < 0)) { if (!copied) copied = bytes_read; @@ -2223,7 +2215,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
copied += bytes_read;
- if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk)) + if (skb_queue_empty(&sk->sk_receive_queue) && __mptcp_move_skbs(sk)) continue;
/* only the MPTCP socket status is relevant here. The exit @@ -2249,7 +2241,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, /* race breaker: the shutdown could be after the * previous receive queue check */ - if (__mptcp_move_skbs(msk)) + if (__mptcp_move_skbs(sk)) continue; break; } @@ -2293,9 +2285,8 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, } }
- pr_debug("msk=%p rx queue empty=%d:%d copied=%d\n", - msk, skb_queue_empty_lockless(&sk->sk_receive_queue), - skb_queue_empty(&msk->receive_queue), copied); + pr_debug("msk=%p rx queue empty=%d copied=%d\n", + msk, skb_queue_empty(&sk->sk_receive_queue), copied);
release_sock(sk); return copied; @@ -2822,7 +2813,6 @@ static void __mptcp_init_sock(struct sock *sk) INIT_LIST_HEAD(&msk->join_list); INIT_LIST_HEAD(&msk->rtx_queue); INIT_WORK(&msk->work, mptcp_worker); - __skb_queue_head_init(&msk->receive_queue); msk->out_of_order_queue = RB_ROOT; msk->first_pending = NULL; WRITE_ONCE(msk->rmem_fwd_alloc, 0); @@ -3407,12 +3397,8 @@ void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags) mptcp_for_each_subflow_safe(msk, subflow, tmp) __mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
- /* move to sk_receive_queue, sk_stream_kill_queues will purge it */ - mptcp_data_lock(sk); - skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue); __skb_queue_purge(&sk->sk_receive_queue); skb_rbtree_purge(&msk->out_of_order_queue); - mptcp_data_unlock(sk);
/* move all the rx fwd alloc into the sk_mem_reclaim_final in * inet_sock_destruct() will dispose it @@ -3455,7 +3441,8 @@ void __mptcp_check_push(struct sock *sk, struct sock *ssk)
#define MPTCP_FLAGS_PROCESS_CTX_NEED (BIT(MPTCP_PUSH_PENDING) | \ BIT(MPTCP_RETRANSMIT) | \ - BIT(MPTCP_FLUSH_JOIN_LIST)) + BIT(MPTCP_FLUSH_JOIN_LIST) | \ + BIT(MPTCP_DEQUEUE))
/* processes deferred events and flush wmem */ static void mptcp_release_cb(struct sock *sk) @@ -3489,6 +3476,11 @@ static void mptcp_release_cb(struct sock *sk) __mptcp_push_pending(sk, 0); if (flags & BIT(MPTCP_RETRANSMIT)) __mptcp_retrans(sk); + if ((flags & BIT(MPTCP_DEQUEUE)) && __mptcp_move_skbs(sk)) { + /* notify ack seq update */ + mptcp_cleanup_rbuf(msk, 0); + sk->sk_data_ready(sk); + }
cond_resched(); spin_lock_bh(&sk->sk_lock.slock); @@ -3725,7 +3717,8 @@ static int mptcp_ioctl(struct sock *sk, int cmd, int *karg) return -EINVAL;
lock_sock(sk); - __mptcp_move_skbs(msk); + if (__mptcp_move_skbs(sk)) + mptcp_cleanup_rbuf(msk, 0); *karg = mptcp_inq_hint(sk); release_sock(sk); break; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 7e2f70f22b05b..e32325417c131 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -124,6 +124,7 @@ #define MPTCP_FLUSH_JOIN_LIST 5 #define MPTCP_SYNC_STATE 6 #define MPTCP_SYNC_SNDBUF 7 +#define MPTCP_DEQUEUE 8
struct mptcp_skb_cb { u64 map_seq; @@ -324,7 +325,6 @@ struct mptcp_sock { struct work_struct work; struct sk_buff *ooo_last_skb; struct rb_root out_of_order_queue; - struct sk_buff_head receive_queue; struct list_head conn_list; struct list_head rtx_queue; struct mptcp_data_frag *first_pending;