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tcp: Rename and small cleanup to tcp_clamp_window()

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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>
This commit is contained in:
David Gibson 2023-11-09 20:53:59 +11:00 committed by Stefano Brivio
parent 2c1554c994
commit 930bc3b0f2
1 changed files with 10 additions and 11 deletions
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21
tcp.c
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@ -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 * @c: Execution context
* @conn: Connection pointer * @conn: Connection pointer
* @window: Window value, host order, unscaled * @window: Window value, host order, unscaled
*/ */
static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn, static void tcp_tap_window_update(const struct ctx *c,
unsigned wnd) struct tcp_tap_conn *conn, unsigned wnd)
{ {
uint32_t prev_scaled = conn->wnd_from_tap << conn->ws_from_tap; uint32_t prev_scaled = conn->wnd_from_tap << conn->ws_from_tap;
int s = conn->sock; int s = conn->sock;
wnd <<= conn->ws_from_tap; wnd = MIN(MAX_WINDOW, wnd << conn->ws_from_tap);
wnd = MIN(MAX_WINDOW, wnd); 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 /* 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 * 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; return;
} }
conn->wnd_from_tap = MIN(wnd >> conn->ws_from_tap, USHRT_MAX);
if (setsockopt(s, SOL_TCP, TCP_WINDOW_CLAMP, &wnd, sizeof(wnd))) if (setsockopt(s, SOL_TCP, TCP_WINDOW_CLAMP, &wnd, sizeof(wnd)))
trace("TCP: failed to set TCP_WINDOW_CLAMP on socket %i", s); 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)) if (ack && !tcp_sock_consume(conn, max_ack_seq))
tcp_update_seqack_from_tap(c, 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) { if (retr) {
trace("TCP: fast re-transmit, ACK: %u, previous sequence: %u", 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 struct tcphdr *th,
const char *opts, size_t optlen) 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); tcp_get_tap_ws(conn, opts, optlen);
/* First value is not scaled */ /* First value is not scaled */
@ -2646,7 +2645,7 @@ int tcp_tap_handler(struct ctx *c, uint8_t pif, int af,
if (!th->ack) if (!th->ack)
goto reset; 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); 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) if (count == -1)
goto reset; goto reset;
/* Note: STALLED matters for tcp_clamp_window(): unset it only after /* Note: STALLED matters for tcp_tap_window_update(): unset it only
* processing data (and window) from the tap side * after processing data (and window) from the tap side
*/ */
conn_flag(c, conn, ~STALLED); conn_flag(c, conn, ~STALLED);