diff mbox series

[mptcp-next,v2,3/7] mptcp: don't always assume copied data in mptcp_cleanup_rbuf()

Message ID 045648bc48950d4d1e78b295131f08b655179c08.1733486870.git.pabeni@redhat.com (mailing list archive)
State Accepted
Commit 11d4943d66ee04356c92f06de54d0e5b332d5146
Delegated to: Matthieu Baerts
Headers show
Series mptcp: rx path refactor | expand

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matttbe/KVM_Validation__debug success Success! ✅
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matttbe/KVM_Validation__btf-debug__only_bpftest_all_ success Success! ✅
matttbe/checkpatch success total: 0 errors, 0 warnings, 0 checks, 64 lines checked
matttbe/shellcheck success MPTCP selftests files have not been modified
matttbe/build success Build and static analysis OK

Commit Message

Paolo Abeni Dec. 6, 2024, 12:10 p.m. UTC 
Under some corner cases the MPTCP protocol can end-up invoking
mptcp_cleanup_rbuf() when no data has been copied, but such helper
assumes the opposite condition.

Explicitly drop such assumption and performs the costly call only
when strictly needed - before releasing the msk socket lock.

Fixes: fd8976790a6c ("mptcp: be careful on MPTCP-level ack.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index bca8c2c046c3..690614816749 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -529,13 +529,13 @@  static void mptcp_send_ack(struct mptcp_sock *msk)
 		mptcp_subflow_send_ack(mptcp_subflow_tcp_sock(subflow));
 }
 
-static void mptcp_subflow_cleanup_rbuf(struct sock *ssk)
+static void mptcp_subflow_cleanup_rbuf(struct sock *ssk, int copied)
 {
 	bool slow;
 
 	slow = lock_sock_fast(ssk);
 	if (tcp_can_send_ack(ssk))
-		tcp_cleanup_rbuf(ssk, 1);
+		tcp_cleanup_rbuf(ssk, copied);
 	unlock_sock_fast(ssk, slow);
 }
 
@@ -552,7 +552,7 @@  static bool mptcp_subflow_could_cleanup(const struct sock *ssk, bool rx_empty)
 			      (ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED)));
 }
 
-static void mptcp_cleanup_rbuf(struct mptcp_sock *msk)
+static void mptcp_cleanup_rbuf(struct mptcp_sock *msk, int copied)
 {
 	int old_space = READ_ONCE(msk->old_wspace);
 	struct mptcp_subflow_context *subflow;
@@ -560,14 +560,14 @@  static void mptcp_cleanup_rbuf(struct mptcp_sock *msk)
 	int space =  __mptcp_space(sk);
 	bool cleanup, rx_empty;
 
-	cleanup = (space > 0) && (space >= (old_space << 1));
-	rx_empty = !__mptcp_rmem(sk);
+	cleanup = (space > 0) && (space >= (old_space << 1)) && copied;
+	rx_empty = !__mptcp_rmem(sk) && copied;
 
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
 		if (cleanup || mptcp_subflow_could_cleanup(ssk, rx_empty))
-			mptcp_subflow_cleanup_rbuf(ssk);
+			mptcp_subflow_cleanup_rbuf(ssk, copied);
 	}
 }
 
@@ -2221,9 +2221,6 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 
 		copied += bytes_read;
 
-		/* be sure to advertise window change */
-		mptcp_cleanup_rbuf(msk);
-
 		if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk))
 			continue;
 
@@ -2272,6 +2269,7 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		}
 
 		pr_debug("block timeout %ld\n", timeo);
+		mptcp_cleanup_rbuf(msk, copied);
 		err = sk_wait_data(sk, &timeo, NULL);
 		if (err < 0) {
 			err = copied ? : err;
@@ -2279,6 +2277,8 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		}
 	}
 
+	mptcp_cleanup_rbuf(msk, copied);
+
 out_err:
 	if (cmsg_flags && copied >= 0) {
 		if (cmsg_flags & MPTCP_CMSG_TS)