6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paolo Abeni pabeni@redhat.com
commit 27b0e701d3872ba59c5b579a9e8a02ea49ad3d3b upstream.
Accessing the transmit queue without owning the msk socket lock is inherently racy, hence __mptcp_check_push() could actually quit early even when there is pending data.
That in turn could cause unexpected tx lock and timeout.
Dropping the early check avoids the race, implicitly relaying on later tests under the relevant lock. With such change, all the other mptcp_send_head() call sites are now under the msk socket lock and we can additionally drop the now unneeded annotation on the transmit head pointer accesses.
Fixes: 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Geliang Tang geliang@kernel.org Tested-by: Geliang Tang geliang@kernel.org Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-1-38ffff5a9ec8@k... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 11 ++++------- net/mptcp/protocol.h | 2 +- 2 files changed, 5 insertions(+), 8 deletions(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1044,7 +1044,7 @@ static void __mptcp_clean_una(struct soc if (WARN_ON_ONCE(!msk->recovery)) break;
- WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); + msk->first_pending = mptcp_send_next(sk); }
dfrag_clear(sk, dfrag); @@ -1588,7 +1588,7 @@ static int __subflow_push_pending(struct
mptcp_update_post_push(msk, dfrag, ret); } - WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); + msk->first_pending = mptcp_send_next(sk);
if (msk->snd_burst <= 0 || !sk_stream_memory_free(ssk) || @@ -1900,7 +1900,7 @@ static int mptcp_sendmsg(struct sock *sk get_page(dfrag->page); list_add_tail(&dfrag->list, &msk->rtx_queue); if (!msk->first_pending) - WRITE_ONCE(msk->first_pending, dfrag); + msk->first_pending = dfrag; } pr_debug("msk=%p dfrag at seq=%llu len=%u sent=%u new=%d\n", msk, dfrag->data_seq, dfrag->data_len, dfrag->already_sent, @@ -2899,7 +2899,7 @@ static void __mptcp_clear_xmit(struct so struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_data_frag *dtmp, *dfrag;
- WRITE_ONCE(msk->first_pending, NULL); + msk->first_pending = NULL; list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) dfrag_clear(sk, dfrag); } @@ -3456,9 +3456,6 @@ void __mptcp_data_acked(struct sock *sk)
void __mptcp_check_push(struct sock *sk, struct sock *ssk) { - if (!mptcp_send_head(sk)) - return; - if (!sock_owned_by_user(sk)) __mptcp_subflow_push_pending(sk, ssk, false); else --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -379,7 +379,7 @@ static inline struct mptcp_data_frag *mp { const struct mptcp_sock *msk = mptcp_sk(sk);
- return READ_ONCE(msk->first_pending); + return msk->first_pending; }
static inline struct mptcp_data_frag *mptcp_send_next(struct sock *sk)