From: Geliang Tang <tanggeliang@kylinos.cn>
v7:
- Patch 1 is a new one to fix the existing issue Sashiko mentioned -
using atomic64_t for msk->ack_seq.
- Fix the map_subflow_seq setting in fallback mode in patch 4.
v6:
- Memory ordering for MPTCP_SYNC_SEQ: Add smp_wmb() before set_bit() in
subflow_set_remote_key() and smp_rmb() after test_and_clear_bit() in
__mptcp_move_skb() and mptcp_release_cb() to prevent data races on
weakly-ordered architectures, ensuring ack_seq updates are visible
before the flag is set and readers see the updated sequence after
observing the flag.
- Lockdep nested locking: Use lock_sock_fast_nested(ssk) instead of
lock_sock_fast(ssk) in mptcp_sock_rate_check_app_limited() to suppress
false positive recursive locking warnings when acquiring subflow socket
locks while holding the parent MPTCP socket lock.
- Receive window advertisement order: Swap mptcp_rcv_space_adjust() and
mptcp_cleanup_rbuf() in mptcp_read_complete() to expand the receive
buffer before evaluating window updates, ensuring ACKs advertise the
new (larger) window size instead of delaying the advertisement until
the next cycle.
- https://patchwork.kernel.org/project/mptcp/cover/cover.1787446274.git.tanggeliang@kylinos.cn/
v5:
- only patch 3 changed.
- Fallback offset underflow: Initialize MPTCP sequence space to 0 in
mptcp_propagate_state() when mp_opt == NULL, ensuring SKB's map_seq
starts from 0 to match msk->copied_seq and prevent offset calculation
underflow in fallback mode.
- Stale peek_seq: Move peek_seq recomputation into the mptcp_move_skbs()
continue path and add another recomputation after sk_wait_data(),
ensuring peek_seq stays synchronized with msk->copied_seq updates from
MPTCP_SYNC_SEQ processing in both paths.
- https://patchwork.kernel.org/project/mptcp/cover/cover.1787368526.git.tanggeliang@kylinos.cn/
v4:
- mptcp_recvmsg: move the peek_seq recompute from after sk_wait_data()
to before the mptcp_move_skbs() continue check.
mptcp_move_skbs() -> __mptcp_move_skb() may shift the head skb's
map_seq to the IASN frame via __mptcp_sync_rcv_sequence(); if
'continue' then exits the loop, the recompute is skipped, and the
next __mptcp_recvmsg_mskq() computes offset with peek_seq in the old
frame minus map_seq in the new frame. The underflow makes the offset
test fail and the skb is skipped (and mptcp_recv_skb() actually frees
the TFO skb via mptcp_eat_recv_skb()).
- Make all three MPTCP_SYNC_SEQ bit accesses atomic:
- subflow_set_remote_key: __set_bit -> set_bit
- __mptcp_move_skb: __test_and_clear_bit -> test_and_clear_bit
- mptcp_release_cb: __test_and_clear_bit -> test_and_clear_bit
The flag is set in BH under mptcp_data_lock() (msk slock held) and
cleared in user context under lock_sock() slow path (only owned=1,
slock not held). The non-atomic RMW on the two sides races, which can
lose the IASN sync.
- https://patchwork.kernel.org/project/mptcp/cover/cover.1787295147.git.tanggeliang@kylinos.cn/
v3:
- Patch 2, handle "offset" in __mptcp_sync_rcv_sequence().
- Patch 3, update __mptcp_move_skb() in response to Sashiko comments:
if (__test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags))
msk->copied_seq += mptcp_iasn(msk);
- Patch 4, replace after64() to after() in mptcp_prune_ofo_queue(). The
pre-existing issue raised by Sashiko regarding changing the type of
ack_seq to atomic64_t is not addressed in this series.
- https://patchwork.kernel.org/project/mptcp/cover/cover.1786445142.git.tanggeliang@kylinos.cn/
v2:
- Patch 3, updated in response to Sashiko comments:
if (unlikely(msk->rcvd_dummy_seq)) {
msk->copied_seq += mptcp_iasn(msk);
__mptcp_sync_rcv_sequence(sk);
/* Release cb() would otherwise re-base copied_seq
* again.
*/
test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags);
}
/* Skip the already peeked data. */
if (offset >= skb->len) {
*last = skb;
continue;
}
- Patch 5, replaced with Paolo's patch.
- Patch 6, 7, new patches addressing app-limited conditions.
- The patch "trim the duplicated skb head at receive enqueue" has been
dropped, as it is no longer needed after Paolo updated the "mptcp:
out-of-order queue pruning" series.
- https://patchwork.kernel.org/project/mptcp/cover/cover.1786158416.git.tanggeliang@kylinos.cn/
v1:
- https://patchwork.kernel.org/project/mptcp/cover/cover.1785150300.git.tanggeliang@kylinos.cn/
The goal of this series is to reduce the differences between TCP and MPTCP
for TLS usage, in preparation for adding TLS over MPTCP support in the
future.
In previous versions [1], a struct tls_prot_ops was defined to represent
the interface differences between TCP and MPTCP, which contained the
following callbacks:
struct sk_buff *(*recv_skb)(struct sock *sk, u32 *off);
bool (*lock_is_held)(struct sock *sk);
void (*read_done)(struct sock *sk, size_t len);
u32 (*get_skb_seq)(struct sk_buff *skb);
int (*skb_get_header)(const struct sk_buff *skb, int offset,
void *to, int len);
bool (*epollin_ready)(const struct sock *sk);
void (*check_app_limited)(struct sock *sk);
In reality, some of these callbacks are unnecessary. This series aims to
eliminate the get_skb_seq(), skb_get_header(), and lock_is_held()
callbacks.
The first four patches come from Paolo's "mptcp: address stall under memory
pressure" series v5 [2], with only minor cleanup from my side.
They remove the CB offset field and sync the MPTCP skb CB layout with the
TCP one, so that we can obtain the TCP or MPTCP sequence number in a
unified way, e.g.:
struct tls_skb_cb {
u32 seq;
};
#define TLS_SKB_CB(__skb) ((struct tls_skb_cb *)&((__skb)->cb[0]))
This eliminates the need for a separate get_skb_seq() callback.
Building on the removal of the CB offset field, I also added patch 5 that
trims the duplicated skb head at receive enqueue. With that in place, KTLS
can retrieve the record header via skb_copy_bits() directly, so there is no
longer any need for a dedicated MPTCP helper like mptcp_skb_get_header().
The skb_get_header() callback can thus be removed.
Patch 6 defers sk_data_ready to the worker, which avoids recursive locking
when TLS calls back into MPTCP under mptcp_data_lock(). With this change,
the lock_is_held() callback is no longer needed and can be removed.
[1]
https://patchwork.kernel.org/project/mptcp/cover/cover.1782123118.git.tanggeliang@kylinos.cn/
[2]
https://patchwork.kernel.org/project/mptcp/cover/cover.1778446731.git.pabeni@redhat.com/
Geliang Tang (3):
mptcp: use atomic64_t for msk->ack_seq
mptcp: track app-limited state in mptcp_sendmsg
selftests: mptcp: sockopt: check app_limited
Paolo Abeni (5):
mptcp: drop the mptcp_ooo_try_coalesce() helper
mptcp: drop the cant_coalesce CB field
mptcp: remove CB offset field
mptcp: sync mptcp skb cb layout with tcp one
mptcp: defer read_sock cleanup to mptcp_worker
include/net/tcp.h | 1 +
include/trace/events/mptcp.h | 4 +-
net/ipv4/tcp.c | 9 +-
net/mptcp/fastopen.c | 17 +-
net/mptcp/options.c | 5 +-
net/mptcp/protocol.c | 287 +++++++++++-------
net/mptcp/protocol.h | 24 +-
net/mptcp/sockopt.c | 2 +-
net/mptcp/subflow.c | 26 +-
.../selftests/net/mptcp/mptcp_sockopt.c | 1 +
10 files changed, 248 insertions(+), 128 deletions(-)
--
2.53.0