From: Christopher Faulet <cfaulet@haproxy.com>
Date: Mon, 27 Nov 2023 16:56:30 +0000 (+0100)
Subject: BUG/MEDIUM: stconn: Don't perform zero-copy FF if opposite SC is blocked
X-Git-Tag: v2.9-dev12~74
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2a307d273acaf382fb035605e76fd9a50b6e74db;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: stconn: Don't perform zero-copy FF if opposite SC is blocked

When zero-copy data fast-forwarding is inuse, if the opposite SC is blocked,
there is no reason to try to fast-forward more data. Worst, in some cases,
this can lead to a receive loop of the producer side while the consumer side
is blocked.

No backport needed.
---

diff --git a/include/haproxy/sc_strm.h b/include/haproxy/sc_strm.h
index c54b6162cb..722662eaa4 100644
--- a/include/haproxy/sc_strm.h
+++ b/include/haproxy/sc_strm.h
@@ -281,6 +281,9 @@ static inline int sc_is_recv_allowed(const struct stconn *sc)
 	if (sc_ep_test(sc, SE_FL_HAVE_NO_DATA))
 		return 0;
 
+	if (sc_ep_test(sc, SE_FL_MAY_FASTFWD) && (sc_opposite(sc)->sedesc->iobuf.flags & IOBUF_FL_FF_BLOCKED))
+		return 0;
+
 	return !(sc->flags & (SC_FL_WONT_READ|SC_FL_NEED_BUFF|SC_FL_NEED_ROOM));
 }