diff mbox series

[net,1/3] mptcp: accurate SIOCOUTQ for fallback socket

Message ID 20220225005259.318898-2-mathew.j.martineau@linux.intel.com (mailing list archive)
State Accepted
Commit 07c2c7a3b622e109ba4d2efd916da0477617ce81
Delegated to: Netdev Maintainers
Headers show
Series mptcp: Fixes for 5.17 | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 17 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Mat Martineau Feb. 25, 2022, 12:52 a.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

The MPTCP SIOCOUTQ implementation is not very accurate in
case of fallback: it only measures the data in the MPTCP-level
write queue, but it does not take in account the subflow
write queue utilization. In case of fallback the first can be
empty, while the latter is not.

The above produces sporadic self-tests issues and can foul
legit user-space application.

Fix the issue additionally querying the subflow in case of fallback.

Fixes: 644807e3e462 ("mptcp: add SIOCINQ, OUTQ and OUTQNSD ioctls")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/260
Reported-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f60f01b14fac..12bb28c5007e 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3294,6 +3294,17 @@  static int mptcp_ioctl_outq(const struct mptcp_sock *msk, u64 v)
 		return 0;
 
 	delta = msk->write_seq - v;
+	if (__mptcp_check_fallback(msk) && msk->first) {
+		struct tcp_sock *tp = tcp_sk(msk->first);
+
+		/* the first subflow is disconnected after close - see
+		 * __mptcp_close_ssk(). tcp_disconnect() moves the write_seq
+		 * so ignore that status, too.
+		 */
+		if (!((1 << msk->first->sk_state) &
+		      (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE)))
+			delta += READ_ONCE(tp->write_seq) - tp->snd_una;
+	}
 	if (delta > INT_MAX)
 		delta = INT_MAX;