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[v3,net-next,3/7] mptcp: fix potential wake-up event loss

Message ID d502c4829953c4e43f429b894ab38a91dbf6da27.1708082765.git.pabeni@redhat.com (mailing list archive)
State Accepted, archived
Commit c64351cfe29e7997b4221db23c38393af1f73cd0
Delegated to: Matthieu Baerts
Headers show
Series mptcp: implement TCP_NOTSENT_LOWAT support | expand

Checks

Context Check Description
matttbe/KVM_Validation__debug__except_selftest_mptcp_join_ success Success! ✅
matttbe/KVM_Validation__debug__only_selftest_mptcp_join_ success Success! ✅
matttbe/checkpatch success total: 0 errors, 0 warnings, 0 checks, 39 lines checked
matttbe/build success Build and static analysis OK
matttbe/KVM_Validation__normal warning Unstable: 1 failed test(s): selftest_mptcp_join

Commit Message

Paolo Abeni Feb. 16, 2024, 11:28 a.m. UTC
After the blamed commit below, the send buffer auto-tuning can
happen after that the mptcp_propagate_sndbuf() completes - via
the delegated action infrastructure.

We must check for write space even after such change or we risk
missing the wake-up event.

Fixes: 8005184fd1ca ("mptcp: refactor sndbuf auto-tuning")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v2 -> v3:
 - drop unused __mptcp_sync_sndnxt() - Mat
---
 net/mptcp/protocol.h | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 486fff865803..738705207652 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -797,6 +797,16 @@  static inline bool mptcp_data_fin_enabled(const struct mptcp_sock *msk)
 	       READ_ONCE(msk->write_seq) == READ_ONCE(msk->snd_nxt);
 }
 
+static inline void mptcp_write_space(struct sock *sk)
+{
+	if (sk_stream_is_writeable(sk)) {
+		/* pairs with memory barrier in mptcp_poll */
+		smp_mb();
+		if (test_and_clear_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags))
+			sk_stream_write_space(sk);
+	}
+}
+
 static inline void __mptcp_sync_sndbuf(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow;
@@ -815,6 +825,7 @@  static inline void __mptcp_sync_sndbuf(struct sock *sk)
 
 	/* the msk max wmem limit is <nr_subflows> * tcp wmem[2] */
 	WRITE_ONCE(sk->sk_sndbuf, new_sndbuf);
+	mptcp_write_space(sk);
 }
 
 /* The called held both the msk socket and the subflow socket locks,
@@ -845,16 +856,6 @@  static inline void mptcp_propagate_sndbuf(struct sock *sk, struct sock *ssk)
 	local_bh_enable();
 }
 
-static inline void mptcp_write_space(struct sock *sk)
-{
-	if (sk_stream_is_writeable(sk)) {
-		/* pairs with memory barrier in mptcp_poll */
-		smp_mb();
-		if (test_and_clear_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags))
-			sk_stream_write_space(sk);
-	}
-}
-
 void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags);
 
 #define MPTCP_TOKEN_MAX_RETRIES	4