When doing a recv(.. MSG_WAITALL) for a message which is larger than

the socket buffer size, the receive is done in sections.  After completing
a read, call pru_rcvd on the underlying protocol before blocking again.

This allows the the protocol to take appropriate action, such as
sending a TCP window update to the peer, if the window happened to
close because the socket buffer was filled.  If the protocol is not
notified, a TCP transfer may stall until the remote end sends a window
probe.

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index ef4ac59..0051121 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -910,6 +910,12 @@ dontblock:
 		    !sosendallatonce(so) && !nextrecord) {
 			if (so->so_error || so->so_state & SS_CANTRCVMORE)
 				break;
+			/*
+			 * Notify the protocol that some data has been
+			 * drained before blocking.
+			 */
+			if (pr->pr_flags & PR_WANTRCVD && so->so_pcb)
+				(*pr->pr_usrreqs->pru_rcvd)(so, flags);
 			error = sbwait(&so->so_rcv);
 			if (error) {
 				sbunlock(&so->so_rcv);