From 930bc3b0f2d2078747172e960807c84a8cd97495 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Thu, 9 Nov 2023 20:53:59 +1100
Subject: tcp: Rename and small cleanup to tcp_clamp_window()
tcp_clamp_window() is _mostly_ about using TCP_WINDOW_CLAMP to control the
sock side advertised window, but it is also responsible for actually
updating the conn->wnd_from_tap value.
Rename to tcp_tap_window_update() to reflect that broader purpose, and pull
the logic that's not TCP_WINDOW_CLAMP related out to the front.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
tcp.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/tcp.c b/tcp.c
index 19d16a6..13e82ca 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1789,19 +1789,19 @@ static void tcp_get_tap_ws(struct tcp_tap_conn *conn,
}
/**
- * tcp_clamp_window() - Set new window for connection, clamp on socket
+ * tcp_tap_window_update() - Process an updated window from tap side
* @c: Execution context
* @conn: Connection pointer
* @window: Window value, host order, unscaled
*/
-static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
- unsigned wnd)
+static void tcp_tap_window_update(const struct ctx *c,
+ struct tcp_tap_conn *conn, unsigned wnd)
{
uint32_t prev_scaled = conn->wnd_from_tap << conn->ws_from_tap;
int s = conn->sock;
- wnd <<= conn->ws_from_tap;
- wnd = MIN(MAX_WINDOW, wnd);
+ wnd = MIN(MAX_WINDOW, wnd << conn->ws_from_tap);
+ conn->wnd_from_tap = MIN(wnd >> conn->ws_from_tap, USHRT_MAX);
/* TODO: With (at least) Linux kernel versions 6.1 to 6.5, if we end up
* with a zero-sized window on a TCP socket, dropping data (once
@@ -1838,7 +1838,6 @@ static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
return;
}
- conn->wnd_from_tap = MIN(wnd >> conn->ws_from_tap, USHRT_MAX);
if (setsockopt(s, SOL_TCP, TCP_WINDOW_CLAMP, &wnd, sizeof(wnd)))
trace("TCP: failed to set TCP_WINDOW_CLAMP on socket %i", s);
@@ -2453,7 +2452,7 @@ static int tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn,
if (ack && !tcp_sock_consume(conn, max_ack_seq))
tcp_update_seqack_from_tap(c, conn, max_ack_seq);
- tcp_clamp_window(c, conn, max_ack_seq_wnd);
+ tcp_tap_window_update(c, conn, max_ack_seq_wnd);
if (retr) {
trace("TCP: fast re-transmit, ACK: %u, previous sequence: %u",
@@ -2538,7 +2537,7 @@ static void tcp_conn_from_sock_finish(struct ctx *c, struct tcp_tap_conn *conn,
const struct tcphdr *th,
const char *opts, size_t optlen)
{
- tcp_clamp_window(c, conn, ntohs(th->window));
+ tcp_tap_window_update(c, conn, ntohs(th->window));
tcp_get_tap_ws(conn, opts, optlen);
/* First value is not scaled */
@@ -2646,7 +2645,7 @@ int tcp_tap_handler(struct ctx *c, uint8_t pif, int af,
if (!th->ack)
goto reset;
- tcp_clamp_window(c, conn, ntohs(th->window));
+ tcp_tap_window_update(c, conn, ntohs(th->window));
tcp_data_from_sock(c, conn);
@@ -2670,8 +2669,8 @@ int tcp_tap_handler(struct ctx *c, uint8_t pif, int af,
if (count == -1)
goto reset;
- /* Note: STALLED matters for tcp_clamp_window(): unset it only after
- * processing data (and window) from the tap side
+ /* Note: STALLED matters for tcp_tap_window_update(): unset it only
+ * after processing data (and window) from the tap side
*/
conn_flag(c, conn, ~STALLED);
--
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