[CCID3]: Use a function to update p_inv, and p is never used

This patch
 1) concentrates previously scattered computation of p_inv into one function;
 2) removes the `p' element of the CCID3 RX sock (it is redundant);
 3) makes the tfrc_rx_info structure standalone, only used on demand.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ccids/ccid3.c

@@ -917,6 +917,7 @@ static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
 				  u32 __user *optval, int __user *optlen)
 {
 	const struct ccid3_hc_rx_sock *hcrx;
+	struct tfrc_rx_info rx_info;
 	const void *val;
 
 	/* Listen socks doesn't have a private CCID block */
@@ -926,10 +927,14 @@ static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
 	hcrx = ccid3_hc_rx_sk(sk);
 	switch (optname) {
 	case DCCP_SOCKOPT_CCID_RX_INFO:
-		if (len < sizeof(hcrx->ccid3hcrx_tfrc))
+		if (len < sizeof(rx_info))
 			return -EINVAL;
-		len = sizeof(hcrx->ccid3hcrx_tfrc);
-		val = &hcrx->ccid3hcrx_tfrc;
+		rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv;
+		rx_info.tfrcrx_rtt    = hcrx->ccid3hcrx_rtt;
+		rx_info.tfrcrx_p      = hcrx->ccid3hcrx_pinv == 0 ? ~0U :
+					   scaled_div(1, hcrx->ccid3hcrx_pinv);
+		len = sizeof(rx_info);
+		val = &rx_info;
 		break;
 	default:
 		return -ENOPROTOOPT;

net/dccp/ccids/ccid3.h

@@ -139,6 +139,8 @@ enum ccid3_hc_rx_states {
  *  @ccid3hcrx_last_counter  -  Tracks window counter (RFC 4342, 8.1)
  *  @ccid3hcrx_state  -  Receiver state, one of %ccid3_hc_rx_states
  *  @ccid3hcrx_bytes_recv  -  Total sum of DCCP payload bytes
+ *  @ccid3hcrx_x_recv  -  Receiver estimate of send rate (RFC 3448, sec. 4.3)
+ *  @ccid3hcrx_rtt  -  Receiver estimate of RTT
  *  @ccid3hcrx_tstamp_last_feedback  -  Time at which last feedback was sent
  *  @ccid3hcrx_tstamp_last_ack  -  Time at which last feedback was sent
  *  @ccid3hcrx_hist  -  Packet history (loss detection + RTT sampling)
@@ -147,13 +149,11 @@ enum ccid3_hc_rx_states {
  *  @ccid3hcrx_pinv  -  Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
  */
 struct ccid3_hc_rx_sock {
-	struct tfrc_rx_info		ccid3hcrx_tfrc;
-#define ccid3hcrx_x_recv		ccid3hcrx_tfrc.tfrcrx_x_recv
-#define ccid3hcrx_rtt			ccid3hcrx_tfrc.tfrcrx_rtt
-#define ccid3hcrx_p			ccid3hcrx_tfrc.tfrcrx_p
 	u8				ccid3hcrx_last_counter:4;
 	enum ccid3_hc_rx_states		ccid3hcrx_state:8;
 	u32				ccid3hcrx_bytes_recv;
+	u32				ccid3hcrx_x_recv;
+	u32				ccid3hcrx_rtt;
 	ktime_t				ccid3hcrx_tstamp_last_feedback;
 	struct tfrc_rx_hist		ccid3hcrx_hist;
 	struct tfrc_loss_hist		ccid3hcrx_li_hist;